Science Is A Verb Vocabulary

Word DefinitionAnalysis The step in the scientific method where data is used to solve a problem.Coefficient The number in FRONT of a formula.Control The conditions which remain constant during the experimentConversion Factor A number or ratio (in fraction form) that is used to convert from one unit

type to another. The given units cancel out, leaving the desired target units.

Data That which is measured or observed during an experiment.Dependent Variable The variable on the Y-axis that changes as a result of changing the

independent variable.Direct Relationship A relationship where the increase of the independent variable results in

the increase of the dependent variable.Experiment An activity designed to test the specifics of the hypothesis.Exponent A number that expresses a “power”, is written as a superscript.Extrapolation Extending the graph beyond the data points to predict values beyond that

which was plotted to get desired information.Given Information which is provided to you in the form of a number and a unit.Hypothesis An “if-then-because” statement used to design an experiment to test an

idea.Independent Variable The variable on the X-axis that the experimenter has control over.Indirect Relationship A relationship where the increase of the independent variable results in

the decrease of the dependent variable, or vice versa.Interpolation Reading between plotted data points on a graph to get desired

information.Line Of Best Fit A straight line that best represents the slope of the data being analyzed.

Can be approximated by hand, or done with linear regression methods.Precision The place to which a measurement was made.Problem A specific issue that can be resolved through application of the scientific

method.Scientific Method A series of logical processes designed to solve problems.Significant Figures The number of digits actually recorded by a measuring device during a

measurement.Target The desired result of a mathematical problem, that which you are solving

for.Unit A symbol which identifies the type of measurement that has been made.

This needs to be placed after every measured number and every calculated answer.

Variable The value that changes during the experiment

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Regents Chemistry FAQ

MATERIALS NEEDED FOR COURSE

- Notebook (spiral, one-subject will be enough)- PENCILS, pens- Pocket folder- Calculator. Graphing calculators may be banned from the Regents Exam, so have a spare scientific calculator handy.- Reference Tables (provided)- One cranial cavity, stuffed full of brains.

Class Guidelines:Guideline Consequence For NoncomplianceBe in your seat ready to work when the bell rings. Late without pass: ½ hour teacher detention in Room 231 that

afternoon (2:20 – 2:50)Cut: Referral to the main office, parent contact

Remain on task for the duration of the period. Parent contact, detention if assigned work not completedRespect the right of all students to learn without distractions or disruptions.

Parent contact½ hour teacher detention in Room 304 that afternoon (2:20 to 2:40)

Food and drink is prohibited. If seen, will be confiscated and disposed of.Hats and portable electronic multimedia and communications devices are prohibited (unless part of a class project presentation).

If seen, will be confiscated and will be turned over to your parents.

WHAT TO EXPECT FROM A TYPICAL CLASS PERIOD

When you enter the class, you will be greeted by some form of review, either questioning, a bell-ringer (limited time to be completed) or a quiz.

At the beginning of each unit, you will receive two packets. The first one contains all of the notes for the unit, including sample problems, diagrams, the unit’s vocabulary words and a schedule for the unit. The second packet contains all of the work that you have to do for the unit. As you finish each topic, you will bring the packet to the front of the room, where it will be checked for correctness. If correct, you will receive point value for the work (usually 10 points) and you may begin the next topic. If incorrect, you will be advised which sections need to be corrected and assistance in correcting those sections. The entire packet is due, complete, no later than test day. Some assignments will be due beforehand, but partial credit will be given if they are turned in by test day. This allows you to work at your own pace, either to stay with the class or work ahead. Assignment correctly completed before being taught in class will receive +2 bonus points. The video tutorials available through my blog and youtube may be of assistance for students looking to get ahead.

The material will be presented to you and you will be given examples of problems to solve or phenomena to explain and apply. Most days, you will be given ample time to complete the assignment in class. Some days, especially right after a test, you will be asked to complete the first topic, almost always an introductory topic, on your own for homework. It is highly recommended that you use a PENCIL to complete all assignments.

At the end of the unit you will be given some review, a practice test for example. The day of the test, we will start by going over the review and then beginning the test.

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IN CLOSING

If asked to refer to a particular reference table, then refer to it. If asked to try solving a problem, then work it out. Participation is required to successfully complete this course. The grade you get in this class is directly related to the amount of effort you put into it. Learning isn’t a spectator sport, and if all you do is sit there and watch you won’t get much out of it. I want you all to do well, and as long as you are working, I can work with you. It is entirely up to you what kind of grade you want to get. You really do have control over your destiny in this class. Take advantage of that fact.

Grading Rubric:

Type Point Value

Notes

In-Class Worksheets 10-30 You will get an assignment packet at the beginning of every unit. You may work ahead if you so desire. The packet is due when you take the unit test. No late packets will be accepted. The packet will be checked on a daily basis to make sure you are doing your work.

Quizzes 10 You will be given a 5-multiple-choice question quiz at the start and end of EVERY DAY. 2 points each. In the event of absence, these quizzes must be made up.

Labs 100 1200 minutes of hands-on lab activities are required to sit for the Regents exam.

Projects 100 Given at various times throughout the year.

Tests 100 Given at the end of every unit. Consists of a multiple-choice section and a short-answer/show-your-work math section. Some tests may forego the multiple-choice section entirely. Some may be take-home tests which will be due two school days after being given.

Breakdown Of Grade Percentages For Marking Period Average:

Test and Quizzes Quarterly Labs Class + Homework40% 20% 20% 20%

Extra Credit: If you complete a day’s assignment correctly before it has been taught, you will get +2 on that page.

Extra Help: Available Tuesdays through Thursdays from 2:20 – 3:10 PM in Room 231. Arrangements for staying later may be made upon request.

Resources Available To You:

Class Blog: Class Packets, Worksheets and summary of class activities

www.mrdonohueschem.wordpress.com

Video tutorials that cover every single topic! (Links will also be made available through the blog)

www.youtube.com/markrosengarten

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Regents Chemistry: TROUBLESHOOTING

PROBLEM SOLUTIONS

I failed a test.

You did not study. Studying does not mean reading your notes. Studying means DOING. Doing your worksheets over again, rewriting your notes into another notebook, using flash cards for vocabulary and other problems are all ways of actively studying. Studying is not a passive task. A sweat should be broken.

But I did study and I sill failed!

Did you seek extra help the day that you didn't understand something? When did you start studying? Your homework period each day should be half studying and half homework. Studying is a cumulative process, not something you spend an hour on the day before the test.

I think I am going to fail the marking period.Did you do all of your homework? Each homework missed can add up to a point or more off your marking period average.

I lost my Reference Tables. Xerox a copy from someone else.I don't know how to use my calculator. Come in and I will show you how.I didn't bring anything to write with. Borrow something from someone in the class. I run out writing

implements. If you borrow one, please return it.I lost the textbook. It will cost you money to replace it.Someone in the family died/was in the hospital/etc. so I couldn't do the homework.

Bring in a note from your parents to let me know that this is a legitimate excuse. Bring homework in next day with the note.

I couldn't do the homework. Did you seek extra help?I don't have the time to come for help. Make the time. There is always time.

I think I am going to fail the Regents exam.

Did you buy a red Barron's book for review? Are you taking all of the old tests and correcting yourself, checking the explanations for the ones you got wrong? This process should start at the beginning of May and go right through to the test.

What is Chemistry?Chemistry is the study of matter, the changes matter undergoes and the energy involved in these changes. It is the universe and how it works, the interactions between particles and energy changes.

Syllabus: units to be taught throughout the year

Science Is a Verb Phases and Phase ChangesThe Atom SolutionsMatter and Energy Kinetics and EquilibriumThe Periodic Table Acids and BasesIonic Bonding ElectrochemistryCovalent Bonding Organic ChemistryEquations and Mole Math Nuclear Chemistry

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Tips for Studying Chemistry:

The point is that the most important variable here is YOUR EFFORT! If your effort is zero, then your grade will be zero.

· I think it is interesting how “A” students tend to get those grades, regardless of the teacher. They take responsibility for their own learning rather than blaming external factors for their lack of success.

Chemistry is different from any other science course you have taken:· The material is new and more abstract, More problem solving, More math.

Therefore, you need to approach Chemistry with a more serious attitude and:1) Be consistent in your study efforts.2) Practice, practice and practice those homework problems!

I find that the most common reasons for failure are:1) Too little study time. We recommend that you study a minimum of 15 minutes per night, for a total of 75 minutes per week. Reading your notes as a method of study is worse than useless…unless you have a photographic memory. ACTIVE studying is the only method that really works.2) Lack of student preparation. Major concern: math skills. You need to be comfortable with numbers and basic algebra.3) Lack of consistent effort. Cramming won’t work well. Study regularly and consistently.4) The wrong approach to studying. Rereading the text and taking notes from the text are not the best way to study. The most important thing you can do for your learning is to do the homework problems and practice tests.5) Overconfidence in understanding the material. It is fine to start solving problems with the teacher’s guidance, but you must put in time at home. On the test, you need to be able to do homework problems without the teacher’s help.

Here are some ideas for ensuring your success in Chemistry:

1) Come to after-school help with specific questions about the course material and homework problems.

2) Rewrite your class-notes and rework through the class exercises.

3) In order to understand a concept rather than simply memorize a definition, try either writing an explanation in your own words or explaining it to someone else.

4) Study groups can be good because many of us learn by talking and discussing. However, beware that this can be a timewaster if you tend to drift away from chemistry.

5) Retake old quizzes, old tests and review sheets.

6) Buy the review book and do the problems in there.

7) Distill your notes into graphic organizers such as attribute webs, flow charts and Venn diagrams.

8) Create a “cheat sheet” in which you will have all of the things you need to know for the test.

9) After doing several problems, create new ones to do by taking existing questions and changing the numbers. When you get good at that, then try creating brand-new problems of your own.

10) Be prepared to do work in class and pay attention to all details being presented. Ask questions when you need to.

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1) Scientific Method

How can problems be solved in a systematic manner?

Scientific MethodYou got a problem? YOU GOT A PROBLEM???? Then solve it, using the Scientific Method! It is a logical sequence of steps designed specifically to solve problems!

Qualities of a ‘good’ experiment Chart

Doctors use the scientific method to diagnose and heal illnesses or injuries.

Politicians use the scientific method to craft their election campaigns.

Arson investigators use the scientific method to determine the cause of fires and determine their point of origin.

Forensic investigators use the scientific method to determine the nature and perpetrators of crime.

Business executives use the scientific method to analyze profit reports and create new business plans.

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While watching the clip from the show Mythbuster, fill in the following chart for their scientific investigation (http://www.youtube.com/watch?v=WpTSA_25wGE)

Problem

Hypothesis

Experiment

Data

Analysis

Further Research

Conclusion

Why did they need to do further testing after their first trial?

What was good about their experiment?

How could their experiment be improved?

Adam says: ‘ [I am astonished] that I am finishing the day calling something plausible that I KNEW wasn’t possible when I woke up this morning’. Do you think there are things that you ‘KNOW’ that just aren’t true?

Question: If a tree starts as a little seed, where does all that ‘stuff’ come from?

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2) Measurement What is the correct way to measure in science?

It should go without saying, but it is very important for scientific investigations that everyone uses the same system and measures in the same way for consistency. Numbers tell us more than you might think. After all, 5g is not the same as 5.0g…

Science uses the Metric System1) Devised in 1960 by the General Conference of Weights and measures2) Called Le Systeme International d'Unites (SI)3) Conversions are all in base 104) Prefixes used to determine the magnitude of a particular unit (Kilo means 1000, centi means 1/100 th)

METRIC UNITS (Reference Table D)

Symbol Name What It Measuresm Meter Distance (length, height, width, from here to there)G Gram Mass (how much matter something contains)Pa Pascal Pressure (force exerted over an area)K Kelvin Temperature (the average kinetic energy of a system)

Mol Mole Amount of substance (6.02 X 1023 things in a mole)J Joule Heat (stored, or potential, energy of a substance)S Second Time (from one point in time to another)L Liter Volume (cubic length: 1 liter = 1 dm3, 1 milliliter = 1 cm3)

Ppm Parts per million Concentration (mass of solute/mass of solvent X 1000000)M Molarity Concentration (moles of solute/L of solution)

METRIC PREFIXES (Reference Table C)

Factor Prefix Symbol Example (Mass) Example (Distance)103 (thousand) Kilo- k 1 kg = 2.2 pounds 1 km = 0.621 miles100 (one) - - 1 g = 0.0353 ounces 1 m = 3.28 feet10-1 (tenth) Deci- d 1 dg = 0.0000353 ounces 1 dm = 3.94 inches10-2 (hundredth) Centi- c 1 cg = 0.00000353 ounces 1 cm = 0.394 inches10-3 (thousandth) Milli- m 1 mg = 0.000000353 ounces 1 mm = 0.0394 inches10-6 (millionth) Micro- 1 g = 0.000000000353 ounces 1 m = 0.0000394 inches10-9 (billionth) Nano- n 1 ng = 0.000000000000353 ounces 1 nm = 0.0000000394 inches10-12 (trillionth) Pico- p 1 pg = 0.000000000000000353 oz. 1 pm = 0.0000000000394 in.

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Math Rules For Chemistry:

1) N3: _______ _______________ _____________________. All measurements and answers to math problems must have units written after the numbers.

2) ______ _____________, ______ _______________. You must show all of the following when doing math problems: the equation you are going to use, the equation rearranged algebraically to solve for the variable you are looking for, the rearranged equation with numbers and units substituted in for all of the variables (numerical setup) and the final answer, rounded properly with units after.

UNCERTAINTY IN MEASUREMENTMeasurements are made one place beyond where the measuring device is marked. For example, a ruler marked to the nearest tenth of a centimeter can be read to the hundredths place by estimating how far between the lines the measurement falls. This is known as the devices ______________________

-------------------------------------

cm 1 2 3 4 5 6 7 8 9 Precision:___________

Device is marked to the ONES place, so read to the __________________ place

Measurement: 6.2 cm the 2 in the tenths place is ESTIMATED

----------------------------

cm .1 .2 .3 .4 .5 .6 .7 .8 .9

Device is marked to the TENTHS place, so read to the ________________________ place

Measurement: 0.48 cm the 8 in the hundredths place is ESTIMATED

DETERMINING PRECISION FROM THE MEASUREMENT:1) If the measurement has a decimal point in it, the precision is the place furthest to the right in the measurement.

In the measurement 23.004 cm, there is a decimal point, so the precision of the measurement is the furthest place to the right, or the thousandths place. 23.004 cm

In the measurement 0.3320 g, there is a decimal point, so the precision of the measurement is the furthest place to the right, of the ten thousandths place. 0.3320 g

In the measurement 330. mL, there is a decimal point, so the precision of the measurement is the furthest place to the right, or the ones place. 330. mL

2) If the measurement does not have a decimal point in it, the precision is the place where either the rightmost integer is, or where a zero with a line over it is.

The measurement 2300 km has no decimal point in it, so the precision is where the rightmost integer is, or the hundreds place. 2300 km _ For the measurement 2300 km, there is no decimal point, so the precision is where the zero with the line over it sits, or the tens place. _

2300 km

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Significant FiguresWhat makes a number ‘significant’? A number is significant if it was directly measured or estimated when taking a measurement. For example:

12000 km: The precision is to the thousands place, therefore the ‘1’ and ‘2’ were directly measured or estimated when this measurement was taken and are significant. The three ‘0’s were neither measured nor estimated and are insignificant. This number has _________ SIG FIGS.

0012000 km: This is the same number as before, except there are two ‘0’s in front of it. These ‘0’s were not measured or estimated and are insignificant. ZERO’s TO THE LEFT OF THE FIRST ‘NUMBER’ ARE NOT SIGNIFICANT. This number would have __________ SIG FIGS.

12000. km: This is not the same number because of the decimal place. The decimal place tells us that the precision was to the ones place, so the ‘0’s in the ones, tens and hundreds places were actually measured to be zero. This means that the three ‘0’s in the ones, tens and hundreds places were actually measured to be zero. This makes them significant. This number would have ___________ SIG FIGS.

In the examples below, the significant figures are underlined and the precision is in bold.

In the measurement 23.285 cm, the first integer is the 2 in the tens place. The precision of the measurement is the thousandths place.

23.28 5 cm five significant figures.

In the measurement 8000 sec, the first integer is the 8 in the thousands place. The precision is the thousands place.

8000 sec one significant figure.

In the measurement 40. L, the first integer is the 4 in the tens place. The precision is the ones place.

4 0 . L 2 sig figs

In the measurement 2300 g, the first integer is the 2 in the thousands place. The precision is the hundreds place.

2 3 00 g two significant figures. _In the measurement 2300 g, the first integer is the 2 in the thousands place. The precision is the tens place. _23 0 0 three significant figures.

In the measurement 200.0 L. the first integer is the 2 in the hundreds place. The precision of the measurement is the tenths place.

200. 0 L four significant figures.

In the measurement 0.713 kg, the first integer is the 7 in the tenths place. The precision is the thousandths place.

0.71 3 kg three significant figures.

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3) RoundingHow do you round off the answers to math problems?

Addition and Subtraction

The answer can only be as precise as the __________ ________________ of the measurements to be added or subtracted. The answer must be rounded to the place of precision of the least precise of the measurements. In the examples, the place of precision is underlined in the measurements.

WHEN ADDING OR SUBTRACTING NUMBERS, RIGHT THERE IN YOUR FACELOOK FOR THE ONE THAT’S __________ _____________ AND ROUND IT TO THAT PLACE!

Round the following number to the

Rounded answer Round the following number to the

Rounded answer

23.337 to the nearest tenth23.3

10000 to the nearest tenth10000.0

23.337 to the nearest hundredth 23.34

10000 to the nearest one10000.

23.337 to the nearest one23

10000 to the nearest ten _10000

23.337 to the nearest ten20

10000 to the nearest hundred

_10000

PLACE CHARTHundred decimal tenThousands thousands tens point hundredths thousandths millionths

3 4 5 6 7 8 . 0 9 8 7 6 5 Ten hundreds ones tenths thousandths hundred Thousands thousandths

Examples:

a) 33.5 cm + 7.88 cm + 0.977 cm = 42.357 cm ROUNDED = 42.4 cm tenths hundredths thousandths Since TENTHS goes out the least far, round the answer to the nearest TENTH.

b) 23000 km + 8.7 km = 23008.7 km ROUNDED = 23000 km thousands tenths Since THOUSANDS goes out the least far, round the answer to the nearest THOUSAND.

c) 6700 mL - 78.7 mL = 6621.3 mL ROUNDED = 6600 mL hundreds tenths Since HUNDREDS goes out the least far, round the answer to the nearest HUNDRED.

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IF YOU HAVE SOME MEASUREMENTS TO MULTIPLY OR DIVIDEROUND TO THE _____________ SIG FIGS, COUNTING FROM THE LEFTWARDS SIDE!

Multiplication and Division

The answer can contain only as many significant figures as the measurement with the least number of significant figures. The sig figs in the following measurements are in bold type.

Round the following number to the

Rounded answer Round the following number to the

Rounded answer

23.337 to 4 sig figs23.34

10000 to 6 sig figs10000.0

23.337 to 3 sig figs 10000 to 5 sig figs

23.337 to 2 sig figs 10000 to 3 sig figs

23.337 to 1 sig figs 10000 to 1 sig fig

a) 67.23 cm X 9.22 cm = 619.584 cm2 ROUNDED = 620. cm2

4 sig figs 3 sig figsRounding the answer to 3 sig figs, you need to put the decimal point to show that the 0 is a sig fig. _b) 200 cm X 3.333 cm = 666.6 cm2 ROUNDED = 670 cm2

2 sig figs 4 sig figsRounding to 2 sig figs makes the ones place a place-holding 0 so that the first two integers are the sig figs.

c) 30 g / 3 mL = 10 g/mL ROUNDED = 10 g/mL 1 sig fig 1 sig fig Sometimes, you don’t need to do anything to your answer. One sig fig is all you need!

d) 30. g / 3.0 mL = 10 g/mL ROUNDED = 10. g/mL 2 sig figs 2 sig figs To show that 10 has 2 sig figs, put a decimal point after the ones place.

e) 30.0 g / 3.00 mL = 10 g/mL ROUNDED = 10.0 g/mL 3 sig figs 3 sig figs To show that 10 has 3 sig figs, take the answer out to the tenths place.

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4) Atomic Structure Essential Question: What is everything made up of?

Atoms are the smallest pieces an element can be broken into and still retain the properties of that element. It comes from the Greek word atomos, meaning “indivisible” (unbreakable).

Atoms are so tiny that they cannot be seen directly. They can be detected through X-ray crystallography or atomic force microscopes, but only indirectly.

It takes 602 000 000 000 000 000 000 000 atoms of hydrogen to weigh 1 gram (the mass of a small paper clip).

Atoms are made up of the following particles:

A) Nucleons (____________________________________________________________________)

1) Protons: have a mass of 1 atomic mass unit (1.66 X 10-24 grams) and a charge of +1. They are found in the nucleus of the atom, and the number of protons in the atom is the atomic number, which identifies what element the atom is. Oxygen (O) has an atomic number of 8, which means there are 8 protons in the nucleus. Since protons are the only particle in the nucleus to have a charge, the charge of the nucleus is + (# of protons). Since oxygen has 8 protons in the nucleus, oxygen has a nuclear charge of +8.

2) Neutrons: have a mass of 1 atomic mass unit, and no charge. They are found in the nucleus of the atom, and the number of neutrons added to the number of protons gives you the mass number of the atom. The number of neutrons does not affect the identity of the element. Oxygen’s most common form has a mass number of 16. Since there are 8 protons in the nucleus of oxygen, this means there must also be 8 neutrons to give a combined mass of 16. The number of protons and neutrons does NOT have to be equal. In addition, atoms of any given element can have differing numbers of neutrons. Atoms of the same element with different numbers of neutrons in their nuclei are called ISOTOPES of one another. The most common isotope is the one who’s mass equals the average atomic mass given on the periodic table rounded to the nearest whole number. Since O has a given average mass of 15.9994, the most common isotope of O is O-16, or Oxygen with a mass number of 16.

B) Particles Outside The Nucleus

3) Electrons: have a mass of 1/1836 amu (9.11×10−28 grams) and a charge of -1. They are found orbiting the nucleus in energy levels. Atoms gain, lose or share electrons when they form chemical bonds. The number of electrons in the atom equals the number of protons. Atoms are neutrally charged, so the + charged protons and the – charged electrons must be equal in number to give a neutral charge. Oxygen has 8 protons in its nucleus, so there must be 8 electrons zipping around outside the nucleus in energy levels. In this unit, the only thing you need to worry about is how to find out how many electrons an atom has, and what the charge and mass of an electron are. Later in the course, you will see just how important electrons are to all of chemistry. They are the part of the atom responsible for all chemical bonding. If it weren’t for electrons, there would be no compounds.

Particles at a glanceProtons Neutrons Electrons

Mass (amu)Charge

Sign

ifica

nce determines the atomic

_____________/__________, nuclear charge and contributes to atomic mass

contributes to atomic ________, number of neutrons varies depending on the _____________

Number of electrons equals number of ____________ for a neutral atom. React with other atoms during reactions.

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Reading the Periodic Table

1) How many protons does an atom of iron (Fe) have? With an atomic number of 26, the atom has 26 protons.

2) What is the nuclear charge of an atom of Fe? Since Fe has 26 protons, the nuclear charge is +26.

3) How many atomic mass units (amu) do the protons in an atom of Fe weigh? Since each proton has a mass of 1 amu, the mass of 26 protons is 26 amu.

4) How many electrons does Fe have around its nucleus? The number of electrons in the atom must equal the number of protons. Since Fe contains 26 protons, it must also contain 26 electrons. If you look at the electron configuration 2-8-14-2 and add up all of those electrons, you will see it adds up to 26 electrons.

5) What is the most common isotope of Fe? Take the average atomic mass of all the isotopes of Fe (55.847) and round it to the nearest whole number (56). That is the mass number of the most common isotope of iron, Fe-56.

6) How many neutrons are in the nucleus of the most common isotope of Fe? To find the number of neutrons, take the mass number (which is the number of particles in the nucleus, protons and neutrons combined) and subtract out the atomic number (the number of protons). There are 56 particles in the nucleus of the most common isotope (Fe-56), of which 26 are protons (from the atomic number of 26). 56 – 26 = 30 neutrons in the nucleus.

A Bit-O-Practice

ElementAtomic Number

Atomic Mass # protons # neutrons #electrons

Nuclear Charge

Number of nucleons

HCOCl

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5) IsotopesWhat is an isotope? ‘Iso’ means ________ ____________, such as in the word ‘isobar’ from earth

science, which was a line of the same pressure (bar = pressure). The thing that is the same for

isotopes is the type of _______________. Not every atom of the same element is identical to

another, their masses can be different. The mass of an atom comes from the mass of the

______________ and _________________. If two atoms are the same element, then they must

have the same number of _________________. For their masses to be different, they must have a

different number of __________________.

Example:

C-12 vs. C-14 Both are isotopes of carbon. C-12 has a mass of 12 amu and C-14 has a mass of 14 amu. Since

they are both carbon, they both have 6 protons. C-12 has a total mass of 12 amu, 6 of which came

from the 6 protons, so it must have 6 neutrons. C-14 has a mass of 14 amu, 6 amu from the

protons and the rest from 8 neutrons.

Fill in the chart for what is the same between C-12 and C-14

Same Different

Distinguishing between different isotopesR 15

It is often required to be specific about what isotope of an element you are referring too and there

are two ways to accomplish this

1) Subscript + Superscript + Symbol: One way to express an isotope is to include the atomic number (_______________), the atomic

mass (______________________) accompanied with the elements symbol.

2) Symbol – Mass: H-1

Because all atoms of the same element have the same atomic __________________, it is often

left out and it can simply be written as the elements symbol - mass

Practice: Complete the chart below

Symbol Atomic # Mass # p n e-

92 143

26 56 26

34 44 36

S-32

82 207 80

30 34 30

35 44 36

6) Weighted Average Mass (WAM): R 16

With all of these different isotopes, how do you determine the average mass for an element?You are taking a class where you have been doing great, except for a single assignment which you

did not do. Your grading breakdown looks like this

You are told to determine your average. For your first attempt at this you simply average the 2

different grades you have:

(100 + 0) / 2 = __________

Realizing that if 90 percent of your grades were 100% right, there is no way that this could be your

overall average. You figure out that you must account for the __________________ of each grade

in your calculations. The way you do this is by multiplying each grade by its percent abundance so

that it reflects all of your good grades. Your second try is more accurate and looks like:

(100 x .90) + (0 x .10) = _____________

Since 90% of your grades were 100, you multiplied 100 by 90%, which is .90 in decimal format.

You did the same for your 0, added the two together and got an overall average of 90%. This is

called your ________________ __________________. You do the same when calculating the

average atomic mass, which is referred to as the Weighted-Average Atomic Mass, or __________

for short. The generic formula for determining the WAM is:

WAM = (massisotope 1 X %/100) + (massisotope 2 X %/100) + (massisotope 3 X %/100) + …

There is one set of parenthesis for each isotope which exists. If there are 2 isotopes, then there will

be 2 sets of parenthesis. If there are 4 isotopes, then there will be 4 sets of parenthesis…etc.

*NOTE: For simplicity, lets round our WAM’s to the thousandths place unless otherwise instructed.

Examples

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GradePercent Abundance

100 90%

0 10%

There are 4 naturally occurring isotopes of Iron. Complete the missing information in the chart below;

Mass of Isotope(amu)

Notation 1

Symbol – mass #

Notation 2

Mass #Symbol

# protons(atomic #)

# neutrons(mass # - atomic #)

# electrons(atomic #)

% Abundance in Nature

54 54Fe 26 54-26 = 28 26 5.845%56 Fe-56 91.754%57 57Fe 2.119%58 Fe-58 0.282%

Calculate the WAM for iron below

Work (multiplying)

Work (adding) Unrounded Answer Rounded w/units

55.90993

LETS TRY ANOTHER ONE!

Nitrogen has 2 naturally occurring isotopes: N-14 (99.33% ) and N-15 (0.67%). What is the WAM for Nitrogen?

Work (multiplying)

Work (adding) Unrounded Answer Rounded w/units

NOTES ABOUT WAM:

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- The rounded atomic mass is the ____________ abundant isotope for that element.

Take a look at the averages in the examples that you did on the previous page. What would happen if you were to round the WAM’s to the ones place? You would get the most abundant Isotope for that element!

- The atomic masses are based on C-12 = 12.000 amu

Protons and neutrons do not weigh exactly 1 amu. Neutrons weigh a tiny fraction _____________ than protons do. An atomic mass unit is actually an average mass, found by taking the mass of a C-12 nucleus and dividing it by 12.

Here are their relative masses

Neutron = 1Proton = 0.99862349Electron = 0.00054386734

Student Name:___________________________________ Grades: _____, _____, _____, _____, _____, _____

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1) Scientific Method Homework1) You arrive home on a lovely Tuesday afternoon and grab your CD player to catch up on some tunes. You slide the headphones on to enjoy the delicious music, but when you press PLAY, nothing happens! You decide to play the scientific method game to figure out what’s wrong.

1) Match the statements below on the right with the parts of the scientific method listed on the left by connecting them with drawn lines:

2) List two other possible hypotheses for why the CD player is not working.

a)________________________________________________________________________________

b)________________________________________________________________________________

3) For one of your hypotheses above, explain how you could work through the scientific method to test the hypothesis:

Chosen Hypothesis:____________________________________________________________________________

Design Experiment to Test Hypothesis:

______________________________________________________________________________________________

______________________________________________________________________________________________

______________________________________________________________________________________________

Expected results if hypothesis is true:________________________________________________________________

______________________________________________________________________________________________

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2) Measurement, Precision and Sig Fig Homework1) Measure the length of a paper clip on each ruler pictured below. The measurements will not be the same for each one, due to a difference in precision. Use the same paper clip for all three measurements and record your readings:

2) For the following measuring devices, record the reading, the precision (place) the measurement was made to and the number of significant figures in the measurement.

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3) Circle the place where the precision is and underline the significant figures in the measurements below. Write the number of significant figures in the measurement to the right of each measurement.

Measurement # Of Sig Figs Measurement # Of Sig Figs Measurement # Of Sig Figs

2 0 0 0 cm 0 . 6 0 0 cm 1 1 . 3 cm

_2 0 0 0 cm 0 . 0 5 0 9 cm 1 1 . 3 0 cm

_2 0 0 0 cm 0 . 4 4 0 0 3 cm 3 cm

2 0 0 0. cm 0 . 0 0 0 0 5 6 cm 3 . 0 cm

2 0 0 0 . 0 cm 0 . 0 0 0 9 9 0 cm 3 . 0 0 7 cm

3 0. cm 2 0 0 . 0 0 6 cm _3 0 0 0 cm

3 2 . 0 cm 3 0 . 0 2 0 cm 9 0 cm

3 3 . 5 cm 9 7 . 2 8 5 cm 3 3 3 0 2 cm

3 9 0 . 0 7 cm 0 . 0 0 9 5 3 cm 6 8 . 0 0 cm

4) Write the following numbers, precise to the noted precision or number of significant figures:

Number Precise to the nearest…

Answer Number Precise to the nearest…

Answer

Forty-two Tenth 42.0 Three hundred twenty

3 sig figs

Three thousand 2 sig figs Seventeen 4 sig figs

0.3 3 sig figs Sixteen thousand

Hundred

Six Thousandth 0.4 Thousandth

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3) Rounding Homework

Be sure to consider the number of significant figures or precision in each of the following problems. For this exercise, consider all numbers to be measurements. Include the units in your answers. Write the UNROUNDED answer first, then the ROUNDED answer, drawing a box around your rounded answer.

1) ADDITIONProblem Unrounded Answer Rounded Answer,

with units4.732 cm + 16.8 cm + 0.781 cm =

32.0 MW + 0.0059 MW =

0.00372 g + 0.2187 g + 0.44 g =

0.0202 km + 0.0303 km + 0.044 km =

345 mmol + 0.788 mmol =

93.667 cg + 81.1 cg =

2) SUBTRACTIONProblem Unrounded Answer Rounded Answer,

with units22.95 mg – 6.4 mg =

33.728 cL – 1.323 cL =

32.32 J – 0.0049 J =

378.98 kg – 16 kg =

1.00345 km – 0.0023 km =

960 cg – 0.00323 cg =

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3) MULTIPLICATIONProblem Unrounded Answer Rounded Answer,

with units37.66 KW X 2.2 h =

14.922 cm X 2.0 cm =

98.11 kg X 200 m =

381 m X 0.21 m =

143 $/L X 341 L =

200. $/kg X 30 kg =

4) DIVISION Problem Unrounded Answer Rounded Answer,

with units4792 g / 24 cm3 =

7139 g / 1426 cm3 =

3.00 cal / 300 g =

19.82 g / 24.2 km =

64.77 g / 9.11 mol =

144.0 g / 10 L

F) OK, here is a practical problem in which you will combine all of your skills. The equation you will use is D = m/v (density = mass / volume). Remember to show a proper numerical setup (with units) and solve, making sure your final answer is properly rounded for the type of math you did:

1) A ring, supposedly made of pure silver (Ag) has a mass of 20.445 grams. When its volume is taken by water displacement, it is found to have a volume of 1.95 mL. Calculate the density of the ring:

2) Based on the actual density of silver (Ag) found on Reference Table S, could this ring actually be made out of silver? Briefly explain your answer:

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Science Is A Verb Review Sheet1) Measure the length of the line below:

2) Complete the following chart:

Measurement Precision # Sig Figs Measurement Precision # Sig Figs2000 cm 0.0302100 cm 0.0012000. cm 0.102030.0 g 0.0003232.00 mL 0.1230320 g 9.0460. mm 9.00371.040 kg 4210

3) Solve and round off the following math problems:

Problem Unrounded Answer Rounded Answer34.21 cm + 1.9 cm =420 kg + 0.23 kg =3.345 mL – 2.8 mL =22.56 g / 9.14 mol =72.35 cm X 2.88 cm =2.34 g / 8.9 mL =23.2 mm X 10 mm =23.2 mm X 10. mm

REVIEW SHEET ANSWERS

Measurement Precision # Sig Figs Measurement Precision # Sig Figs2000 cm thousand 1 0.030 Thousandth 22000 cm Thousand 1 0.001 Thousandth 12000. cm One 4 0.1020 Ten thou’th 430.0 g Tenth 3 0.00032 Hund tho’th 232.00 mL Hundredth 4 0.1230 Ten thou’th 4320 g Ten 2 9.0 Tenth 2460. mm One 3 9.00 Hundredth 3371.040 kg thousandth 6 4210 Ten 3

Problem Unrounded Answer Rounded Answer34.21 cm + 1.9 cm = 36.11 36.1 cm420 kg + 0.23 kg = 420.23 420 kg3.345 mL – 2.8 mL = 0.545 0.5 mL22.56 g / 9.14 mol = 2.468271335 2.47 g/mol72.35 cm X 2.88 cm = 208.368 208 cm2

2.34 g / 8.9 mL = 0.262921348 0.26 g/mL23.2 mm X 10 mm = 232 200 mm2

23.2 mm X 10. mm 232 230 mm2

4) Atomic Structure (The Nucleus) Day 1R 25

A) Multiple-Choice Questions: place your answers in the space to the left of each question.

_____1) One atomic mass unit is defined as weighinga) 1/16 the mass of O-16 b) 1/12 the mass of C-12c) 1/32 the mass of S-32 d) 1/10 the mass of B-10

Where do you find this information on the Periodic Table?

_____2) How many electrons does it take to weigh the same as a proton?a) 1 b) 100 c) 957 d) 1836

_____3) Carbon-12 contains 6 protons, 6 neutrons and 6 electrons. Which subatomic particle, if changed, would change the identity of the element?a) proton b) neutron c) electron d) all of the above

_____4) A nucleus of Mg-25 contains how many neutrons?a) 12 b) 13 c) 25 d) 37

Explain how you reached this determination.

_____5) What is the nuclear charge of a nucleus of P-32?a) +15 b) +17 c) +32 d) +47

Explain how you reached your conclusion.

_____6) How many electrons orbit a nucleus of N-13?a) 6 b) 7 c) 13 d) 19

Explain why this is.

B) Complete the following table:

Isotope # Protons # Neutrons # Electrons Nuclear Charge39

19K42

20Ca56

26Fe232

92U

4) Atomic Structure (The Nucleus) Day 2R 26

_____A) Which of the following represents isotopes of the same element?a) 8

18O and 818O b) 8

16O and 818O

c) 818O and 9

18F d) 919F and 10

19Ne

Explain why the two symbols represent isotopes of the same element:

Explain why ONE of the other choices are NOT isotopes of the same element.

B) Find the most common isotope for each of the following elements:

Element Atomic Mass (from Periodic Table) Most Common Isotope

Ca 40.08 Ca-40BrZnHgD) Weight-Average Mass Problems (show all work, round your answer to the thousandths place):

1) A meteor crashes to Earth, is collected and analyzed. To everyone’s surprise, a new element is discovered with an atomic number of 120. Calculate the weight-average atomic mass for this new element, Ubn (Unbinnulium). Show all work below.

2) Honors/Bonus. The average atomic mass for thallium, Tl, is 204.41. There are 2 isotopes; Tl-203 and Tl-205. What is the percent abundance of each isotope?

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