honors atomic class packet unit 3 - ms. drury's flipped ... · web viewthe sum of the protons...

Honors Atomic Class Packet Unit 3

Key Ideas The modern model of the atom has evolved over a long period of time through the work of many scientists.(3.1a) Each atom has a nucleus, with an overall positive charge, surrounded by one or more negatively charged electrons. (3.1b) Subatomic particles contained in the nucleus include protons and neutrons. (3.1c) The proton is positively charged, and the neutron has no charge. The electron is negatively charged.(3.1d) Protons and electrons have equal but opposite charges. The number of protons equals the number of electrons in an atom.

(3.1e) The mass of each proton and each neutron is approximately equal to one atomic mass unit. An electron is much less

massive than a proton or a neutron. (3.1f) The number of protons in an atom (atomic number) identifies the element. The sum of the protons and neutrons in an

atom (mass number) identifies an isotope. Common notations that represent isotopes include: 14C, 14C, carbon-14, C-14. (3.1g)

In the wave-mechanical model (electron cloud model), the electrons are in orbitals, which are defined as the regions of the most probable electron location (ground state). (3.1h)

Each electron in an atom has its own distinct amount of energy. (3.1i) When an electron in an atom gains a specific amount of energy, the electron is at a higher energy state (excited state). (3.1j) When an electron returns from a higher energy state to a lower energy state, a specific amount of energy is emitted. This

emitted energy can be used to identify an element. (3.1k) The outermost electrons in an atom are called the valence electrons. In general, the number of valence electrons affects the

chemical properties of an element. (3.1l) Atoms of an element that contain the same number of protons but a different number of neutrons are called isotopes of

that element. (3.1m) The average atomic mass of an element is the weighted average of the masses of its naturally occurring isotopes. (3.1n) The placement or location of elements on the Periodic Table gives an indication of physical and chemical properties of that

element. The elements on the Periodic Table are arranged in order of increasing atomic number. (3.1y) For Groups 1, 2, and 13-18 on the Periodic Table, elements within the same group have the same number of valence

electrons (helium is an exception) and therefore similar chemical properties. (3.1z)

Introduction to Subatomic Particles

1


A scientist, John Dalton presumed atoms were the smallest particle in the universe and stated that they were small hard spheres. Years later J.J. Thompson was experimenting with an apparatus known as the cathode ray tube (used in old Tvs!). He evacuated the chamber of any known substances and passed electricity through it. He was shocked to see a glowing green light. He noticed the green light was flowing towards the positive electrode of his tube. He discovered the first particle inside “the smallest particle” and it was later called an electron.

1. What is the charge of an electron, according to the saying “opposites attract?”

The student of Thompson, Ernest Rutherford, sets up an experiment to determine if the atom is in fact the smallest particle. He decided to shoot lasers at gold foil. Read about it below:

Ernest Rutherford performed the “Gold Foil” experiment in 1911 which helped him develop the “solar system’” or “nuclear” model of the atom. He used alpha particles (small but dense positive charged particles emitted like x-rays) and shot them at gold foil. He assumed that either the particles would go straight through the foil like an x-ray through a person’s skin, or they would be deflected back like x-rays on the lead suit you wear at the dentist. So he placed a detection chamber around his experiment to detect the alpha particles (and to shield himself from the radiation).

2. If you threw a stream of tennis balls at a brick wall what would happen?

3. If you threw a stream of tennis balls at smoke what would happen?

4. If Dalton’s model is correct and the atom is a solid sphere; when alpha particles (tennis balls) were shot at the gold foil (wall), what should happen?

5. If Thompson’s model is correct and the atom is a positive cloud (smoke) with electrons scattered throughout; when alpha particles (tennis balls) were shot at the cloud (smoke), what should happen?

6. When Rutherford performed his experiment, for every 100 alpha particles, only one particle was deflected. All other 99 particles travelled straight through the foil.

a. What does deflected mean?

b. Was the probability of hitting the nucleus high or low?

c. Does that mean the nucleus is small or large?*

2

- +


d. Is that atom mostly solid or mostly empty?*

e. Rutherford knew the alpha particles are positive and they were deflected by the nucleus, rather than attracted to it. What is the charge of the nucleus?*

f. If the nucleus deflected the alpha particles, was it massive or not?*

g. Where could the negatively charged electrons be?

h. Are the electrons massive? How can you tell?

7. Put all the questions with an asterisk (*) next to them together to explain Rutherford’s results.

8. Watch the demonstration performed by your teacher about centripetal force.i. Negative electrons attract positive protons. So why don’t electrons collapse into the nucleus?

j. Draw the Rutherford model labeling the protons, neutrons, electrons, nucleus and how alpha particles may be deflected or go straight through.

3


Scientist Practice

1.) J.J. Thomson’s Cathode Ray Tube experiment led to the discovery of1. the positively charged subatomic particle called the electron2. the positively charged subatomic particle called the proton3. the positively charged subatomic particle called the electron4. the negatively charged subatomic particle called the electron

2.) According to the Bohr Model,1. electrons are found in areas of high probability called orbitals2. electrons travel around the nucleus in circular paths called orbits3. electrons are found in areas of high probability called orbits4. electrons travel around the nucleus in random paths called orbitals

3.) According to the Wave-Mechanical Model,1. electrons are found in areas of high probability called orbitals2. electrons travel around the nucleus in circular paths called orbits3. electrons are found in areas of high probability called orbits4. electrons travel around the nucleus in random paths called orbitals

4.) In Thomson’s cathode-ray experiment, what evidence led him to believe that the ray consisted of particles, and why did he conclude that the ray was negatively charged?

5.) One model of the atom states that atoms are tiny particles composed of a uniform mixture of positive and negative charges. Scientists conducted an experiment where alpha particles were aimed at a thin layer of gold atoms. Most of the alpha particles passed directly through the gold atoms. A few alpha particles were deflected from their straight-line paths. An illustration of the experiment is shown below.

a. Most of the alpha particles passed directly through the gold atoms undisturbed. What does this evidence suggest about the structure of the gold atoms?

b. A few of the alpha particles were deflected. What does this evidence suggest about the structure of the gold atoms?

c. How should the original model be revised based on the results of this experiment?

6.) In 1897, J. J. Thomson demonstrated in an experiment that cathode rays were deflected by an electric field. This suggested that cathode rays were composed of negatively charged particles found in all atoms. Thomson concluded that the atom was a positively charged sphere of almost uniform density in which negatively charged particles were embedded. The total negative charge in the atom was balanced by the positive charge, making the atom electrically neutral. In the early 1900s, Ernest Rutherford bombarded a very thin sheet of gold foil with alpha particles. After interpreting the results of the gold foil experiment, Rutherford proposed a more sophisticated model of the atom.

a. State one conclusion from Rutherford’s experiment that contradicts one conclusion made by Thomson.

b. State one aspect of the modern model of the atom that agrees with a conclusion made by Thomson.

4


Subatomic Particles Practice to make PermanentSubatomic particles are the smaller objects inside the atom: protons, neutrons and electrons!

Directions: Under the headings, explain how to obtain each piece of data. Then based on the information given in the row, determine the element and its contents, thus filling out the entire chart.

Name Symbol Protons Neutrons Electrons Atomic # Mass #

Hydrogen 0 1 1

He 2 4

Carbon C 6 12

Nitrogen 7 7 7

Oxygen O 8 8 8

Aluminum 14 13 27

Iron 26 30

Co 27 59

Lithium 4

Beryllium Be 4 4 9

Boron 5 11

Ne 10

Sodium 11 12

Fluorine 9 10

Nickel Ni 59

Ca 40

5


IonsCations are _____________ charged because they _______________ _______________ when bonding.

(positively/negatively) (gain/lose) (electrons/protons)

Anions are _____________ charged because they _______________ _______________ when bonding. (positively/negatively) (gain/lose) (electrons/protons)

If a particle has 9 protons and 10 electrons, what is the symbol and charge? ___________ If a particle has 11 protons and 10 electrons, what is the symbol and charge? ___________ If a particle has 12 protons and 10 electrons, what is the symbol and charge? ___________

Give a mathematical rule for determining the charge of a particle: ____________________________________

Name Symbol Protons Neutrons Electrons Atomic # Mass #

Copper ion Cu+2 29 35 64

Barium ion Ba+2 56 137

K+ 39

Gold ion Au+3 118 79

Chloride ion 18 18 17

Fluoride ion F- 10

Sulfide ion S-2 16

O-2 16

Aluminum ion 13 10 27

6


Subatomic Particles Regents Questions

7


Nuclear Charge

The term nuclear charge represents the number and sign of the charge inside the nucleus. Protons which are __________________ charged and neutrons which are __________________ charged, are in the nucleus. This means the nucleus is always ______________ charged. Complete the table below (all are neutral):

Name Symbol Protons Neutrons Electrons Atomic # Mass # Nuclear charge

Oxygen 8 8 8 16 8+

7 7 7

S 34

Hydrogen (deuterium) 1 1 1

Hydrogen (tritium) 1 1 3

9 19

Beryllium 9

12 24

12 25

92 238 92+

Chlorine 35

17 37

Kr 36 84

26 56

Silver 60

Some of these examples are the same element. What was different about them? _______________________

_________________________________________________________________________________________

8


Isotopes

In terms of subatomic particles, isotopes are atoms of the same element which have a different number of

___________________ but the same number of ________________. Thus the ___________________ number

is the same but the ______________ number is different. Isotope names can be followed by the mass number.

Example: Carbon -14 and Carbon-12. Isotope symbols include the element’s symbol with the mass number on

the top left and the atomic number on the bottom left. Example: 146C and 12

6C

Name-Mass Number Isotope Symbol

Mass Number

Atomic Number Neutrons Protons Electrons Nuclear

ChargeLithium-6

Lithium-7

Boron-10

Boron-11

Sodium-22

Sodium-24

Aluminum-26

Aluminum-27

Iron-55

Iron-56

Zinc-65

Zinc-66

For each pair above, look up the element’s atomic mass from the reference table and decide which isotope is more abundant. Circle the more abundant isotope’s name.

9


Atomic Mass

In class the following grades were reported:

Grade out of 50 % of students

50 10

45 25

40 40

35 20

30 5

1. Calculate the class average and show your work.

2. The teacher uses the following calculation:

50(.10) + 45(.25) + 40(.40) + 35(.20) + 30(.05) = Class Average out of 50

a. Finish her calculation in your calculator. Class average: __________________

b. Explain how she completed the calculation and why it works.

__________________________________________________________________________________________

The atomic mass is the weighted average mass of the naturally occurring isotopes of an element. It can be found by multiplying the mass number of the atom by the percent abundances (in decimal form) and adding the results.

Example: Copper-63 and Copper-65 are 69.17% and 30.83% respectively. What is the atomic mass?

63(.6917) + 65(.3083) = 63.5 amu How is this similar to the calculation you did above?

Find the atomic masses of the following:

1. Silver : 55.0% Ag-107, 45.0% Ag-109

2. Indium : 40.0% In-113, 60.0% In-115

10


3. Rhendium : 30.0% Re-185, 70% Re-187

4. Copper : 75.0% Cu-63, 25.0% Cu-65

5. Chlorine : 75.5% Cl-35, the rest Cl-37

6. Lithium : 7.4% Li-6, the rest Li-7

7. Boron : 19.6 % B-10, the rest B-11

8. Oxygen : 99.76% O-16, 0.046% O-17, and 0.20% O-18

Sometimes a more specific mass is given for the mass number. Continue the same steps you did above!

9. Naturally occurring chlorine that is put in pools is 75.53% Cl-34.969 and 24.47% Cl-36.9666. Calculate the atomic mass.

10. Copper is used in electric wires and comes as two isotopes, Cu-63 and Cu-65. Cu-63 has an actual mass of 62.9298amu and Cu-65 has an actual mass of 64.9233 amu. If they are 69.09% and 30.91% abundant respectively, what is the atomic mass?

11. BONUS: Magnesium has three isotopes Mg-24 (78.70%), Mg-25 (10.13%), and Mg-26 (11.7%). The actual mass of Mg-25 is 24.98584 and the actual mass of Mg-26 is 25.98259. What is the actual mass of Mg-24 if the atomic mass of magnesium equals 24.3050 amu?

11


MASS SPECMass Spectrometry, Percent Abundance & Atomic Mass

Mass spectrometry is a technique used in chemistry to determine average atomic mass values for the elements. It can also be used to identify unknown compounds, such as in forensics and archeology.

Mass Spectrometer

Mass Spectrometer Reading for Neon

For example: Which mass spectrometer reading represents naturally occurring magnesium?

12

How a Mass Spectrometer Works:• A gaseous sample is hit with electrons, which produces

positive ions • These positive ions are sent through a magnetic field, which

exerts a force on the charged ions• The ions are deflected by the force of the magnetic field and

hit a film on the other side of the magnetic field – this is how they are detected

• The lighter (less massive) particles are affected by the force of the magnetic field more than the heavier particles, and so will be deflected more from the straight-line path.

• By comparing the amount or degree of deflection for the particles in a sample of a given element to the standard deflection angles for a sample of carbon-12, atomic masses* can be determined. *These are relative atomic masses – relative to the standard (carbon-12).

• From the number of hits at each deflection point, the relative abundances of the isotopes in the sample can be determined.

How to Read a Mass Spectrogram:• A peak indicates that particles with that mass number were

detected• The taller the peak, the more particles there were in the sample

with that particular mass• This spectrogram for neon shows a very tall peak at mass = 20 and

a short peak at mass = 22. This means that there were more neon-20 atoms than neon-22 atoms. The neon-20 isotope contributes more to the average atomic mass for neon because there are more atoms of neon-20 than neon-22. Looking up the average atomic mass for neon on the Ref. Tables, we find that it is 20.18 amu, which makes sense because there are many more neon-20 atoms than neon-22 atoms, making the average atomic mass closer to 20 than to 22.


1. An unknown element ‘Z’ is analyzed in a mass spectrometer and is found to have the following isotopes with the corresponding relative abundances.

Isotope Z Relative Abundance50 Z 4.3452 Z 83.7953 Z 9.5054 Z 2.37

(a) Sketch the expected mass spectrum that these data would provide. Label the axes and pay attention to the size of any lines that you draw.

(b) Calculate the average atomic mass of Z and identify the element.

2. Consider the following mass spectrum that was generated from the analysis of an element. What does the existence of only a single peak in the spectrum suggest about the element? What is the element’s identity?

100

RelativeAbundance

024 25 26 27 28

m/z

13


14

For each graph on this page, choose which element matches the graph. Your choices include:

Hg, Li, Mg, B, Cl, Zr, Mo


15

Calculate the average atomic mass and identify the element.

Calculate the average atomic mass and identify the element.


Isotopes/Atomic Mass Regents Questions

16


17


Bohr Diagrams

Bohr diagrams show the number of protons and neutrons in the nucleus and the number of electrons in their energy levels. The electron configuration shows how many electrons are in each level in the ground state, or under normal conditions. An example of a Bohr diagram is given below:

Draw the Bohr diagrams of the following:

H-1 K-40 Li-7 Be-9

B-11 C-14 Ne-20 O-16

F-19 Cl-35 Al-27 S-28

S-32 N-14 Mg-24 P-31

Valence electrons are the electrons in the outermost shell. They are the furthest from the nucleus, escaping the protons pulling on them. Therefore, they have the __________ energy out of all the electrons. Do any of the elements above have the same number of valence electrons? List the pairs:

18

Magnesium (Mg)Atomic number 12Mass number (rounded) 24 12p+, 12 e-, 12no

12p+

12n0

21

81

21


Spectra

1. State the total number of valence electrons in a cadmium atom in the ground state.

2. Identify all the elements in the mixture shown above.

__________________________________________________________________________________________The Balmer series refers to the visible bright lines in the spectrum produced by hydrogen atoms. Thecolor and wavelength of each line in this series are given in the table below.

3. Explain, in terms of both subatomic particles and energy states, how the Balmer series is produced.

4. Recreate diagram above and draw four vertical lines to represent the Balmer series.

__________________________________________________________________________________________5. Write an appropriate number of electrons in each shell to represent a Mg-26 atom in an excited state.

6. What is the total number of valence electrons in an atom of Mg-26 in the ground state?_________

19


Many advertising signs depend on the production of light emissions from gas-filled glass tubes that aresubjected to a high-voltage source. When light emissions are passed through a spectroscope, bright-linespectra are produced.

7. Explain the production of an emission spectrum in terms of the energy states of an electron.

8. Identify the two gases in the unknown mixture.

__________________________________________________________________________________________9. Electron transitions from one shell to another are given for four different atoms below:

Atom G: 3rd shell to 2nd shell Atom I: 4th shell to 6th shellAtom H: 1st shell to 4th shell Atom J: 5th shell to 3rd shell

a. In which atom(s) is energy absorbed during the e- transition?

b. In which atom(s) is energy released during the e- transition?

c. In which atom(s) would spectral lines be observed?

d. In which atom is the greatest amount of energy absorbed?

e. In which atom is the greatest amount of energy released?

f. In atom G, compare the energy of the electron in the 3rd shell to that of the electron in the 2nd shell.

20


Lewis DiagramsLewis diagrams show only the atom’s symbol and dots representing the valence electrons. The most valence electrons an atom can have is ____ so the most dots you will draw is ____. Please make dots very visible!

Examples:

Name Protons Neutrons ElectronsElectron

Configuration

Valence

Electrons

Lewis

Diagram

Rubidium-85

Cesium-133

Strontium-88

Barium-138

Germanium-72

Tin-119

Arsenic-75

Antimony-121

Sellenium-79

Tellurium-127

Bromine-80

Iodine-127

Xenon-131

Krypton -84

1. Why are the valence electrons the most important electrons? _________________________________

2. What do elements with the same valence electrons have in common? ___________________________

3. The kernel electrons are all electrons except the valence electrons. How many kernel electrons does

magnesium have? _____________________________________________________________________

4. Draw the Lewis dot diagram of Li+, Ca+2, S-2 and F-

5. All cations have _________ dots and all anions have _______ dots.

21


ELECTRON CONFIGURATIONS

Full e- Configuration # Valence e-

Valence orbital notation Lewis Diagram

H

He

Li

Be

B

C

N

O

F

Ne

Mg

Si

S

Ar

K

Fe

Zn

As

Br

Sr

Zr

Te

Xe

22


IONS AND EXCEPTIONS

Atom’s e- Configuration(Noble Gases Short Cut Allowed)

# Valence e-

Ion’s e- Configuration(Noble Gases Short Cut Allowed)

Ion’s Lewis

DiagramLi+

Cu+2

Co+3

Mg+2

Sc+2

Na+

Ag+

Ca+2

O-2

Zn+2

K+

Br-

As-3

Cu+1

Au+

N-3

Mo+

S-2

F-

As+5

P-3

As+3

1. Explain why arsenic can form three different ions in terms of valence electrons and stability.

2. Explain why more transition metals have two valence electrons with the exception of groups 6 and 11.

23


3. The electron configuration 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 has _____ unpaired electrons and

represents element _________________.

4. The electron configuration 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p2 has _____ unpaired electrons and represents

element ______________________.

5. Which electron configuration(s) are in the excited state? Circle all that apply:

1s2 2p6 3s2 3p6 4s2 3d10 4p2 1s2 2s2 2p6 3s2 3p1

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p2 1s2 2p6 3s2 3p6 4s2 3d10 4p2

1s2 2s2 2p6 3s2 4s2 3d10 4p2 1s2 2s2 2p6 3s1

1s2 2s2 2p6 3s2 3p5 4s2 3d10 4p2 1s2 2s2 2p6 3s3

1s2 2s2 2p6 3s2 3p6 4s2 3d8 1s2 2s2 2p6 3s2 3p8

1s2 2s2 2p6 3s2 3p6 4s2 3d5 1s2 2s2 3s2

6. Where any of the above configurations not allowed? Box them and explain their errors.

7. Draw shapes for the s p and d orbitals.

8. How many electrons can fill each orbital? Why? (Give a rule and explanation)

9. How many electrons fill the s orbital? ____

10. How many electrons fill the 4p sublevel? ____

11. How many electrons fill the 3d sublevel? ____

12. How many electrons fill the 5f sublevel? ____

13. How many electrons will fill a p orbital? ____

14. Which rule states that the 3d must be filled using a 4s electron for Copper? ______________________

15. What is the term given to describe that all 3d orbitals have the same energy? _____________________

24


ELECTRON CONFIGURATIONS PRACTICE

1. Give full and abbreviated (noble gas core method) electronic configurations for the following.

(a) Br FULL ______________________________

NOBLE GAS CORE ______________________________

(b) Cr FULL ______________________________

NOBLE GAS CONF ______________________________

(c) Fe FULL ______________________________

NOBLE GAS CONF ______________________________

(d) S2- FULL ______________________________

NOBLE GAS CONF ______________________________

2. For each of the following sets of orbitals, indicate which orbital is higher in energy.(a) 1s, 2s _________ (c) 4s, 3dyz _________

(b) 2p, 3p _________ (d) 3px, 3py, 3pz _________

3. Indicate the block (s, p or d) in which each of the following elements found. (a) Sc ______ (d) Ni ______

(b) P ______ (e) As ______

(c) Fr ______ (f) Sr ______

4. An atom has two electrons with principal quantum number (n) = 1, eight electrons with principal quantum number (n) = 2 and seven electrons with principal quantum number (n) = 3. From these data, supply the following values

(a) The mass number _________

(b) The atomic number _________

(c) The electron configuration ___________________________

5. Identify the element from the electron configurations of atoms shown below.(a) [Ne] 3s2 3p2 _________

(b) [Ar] 4s2 3d7 _________

(c) [Xe] 6s2 _________

25


6. Give the symbol of the atom or ion represented by the following sets of atomic numbers and configurations.Atomic # Electronic Configuration Symbol of Atom or Ion

(a) 8 1s2 2s2 2p4 ________

(b) 11 1s2 2s2 2p6 ________

(c) 14 1s2 2s2 2p6 3s2 3p2 ________

(d) 22 1s2 2s2 2p6 3s2 3p6 3d2 ________

7. Give the electron configurations for the following transition metal ions.(a) Sc3+ __________________________________(b) Cr2+ __________________________________(c) Ni3+ __________________________________

8. Consider the element Scandium, atomic # 21.(a) If the configuration of the element were constructed, into which orbital would the final electron be placed?

(b) When scandium forms an ion with a charge of +1, from which orbital would the electron be removed?

9. Of the following species (Sc, Ca2+, Cl, S2-, Ti3+), which are isoelectronic? ____________________________

10. Identify the element that is composed of atoms where the last electron;

(a) Enters and fills the 4s sub-shell ________

(b) Enters but does not fill the 4s sub-shell ________

(c) Is the first to enter the 2p sub-shell ________

(d) Is the second to enter the 4d sub-shell ________

11. Write the full electronic configuration for argon. _______________________________________________

12. Identify two positive and two negative ions that are isoelectronic with argon.

26


Unit 3 Atomics Review

SCIENTIFIC THEORIES

Dalton theorized that atoms were the smallest particle and could not be divided. Atoms can bond with one another in whole number ratios to form compounds but cannot be created or destroyed. Atoms of the same element are identical. Dalton’s model is known as the hard sphere model.

a. According to Dalton, what is inside the atom? ___________________________________________

b. What part of Dalton’s theory has been disproven? ________________________________________

Thompson worked with the cathode ray tube and discovered a ray of light travelling to the positive plate in the tube. This particle was the electron which must have a negative charge. Because atoms are neutral, Thompson assumed there must be invisible positively charged particles as well. These discoveries lead to Thompson’s plum pudding model.

a. Draw the plum pudding model:

b. Explain why Thompson concluded that electrons are negative. ____________________________________________________________________________________

Rutherford shot alpha particles at gold foil in an effort to disprove either Dalton or Thompson’s theory. If Dalton were right, the alpha particle would deflect, if Thompson were right the alpha particle would go straight through. 99% of the alpha particles went straight through. Rutherford concluded the atom was mostly empty space with a dense positive nucleus containing protons and neutrons. His model is known as the nuclear model.

a. Draw the nuclear model:

b. If alpha particles are positive and bounce off of the nucleus, what is the charge of the nucleus?

_____________________________________________________________________________

Bohr used complicated mathematics to organize electrons into orbits around the nucleus with specific energies. His model is known as the planetary model.

a. Draw the planetary model:

b. Have the placement of p+ and no changed in Bohr’s model since Rutherford’s model?

____________________________________________________________________________________

27


SUBATOMIC PARTICLES

Atoms are neutral and contain subatomic particles. Protons are positively charged particles located in the nucleus. Neutrons are neutral particles located in the nucleus. Electrons are negatively charged particles found in orbit around the nucleus. Protons and neutrons both weigh 1 amu and the electron’s mass in negligible.

a. Fill in the chart below:

Charge Mass Location

Proton

Neutron

Electron

b. What is an amu? ___________________________________________________________________

c. What does “the electron’s mass in negligible” mean? _____________________________________

d. If atoms are neutral, then the number of protons _________ the number of electrons because

___________________________________________________________________________________

The atomic number is the identity of an element. The periodic table and table S are arranged according to the

atomic number. It tells you how many protons an atom has.

a. Which element has 36 protons? _____________

b. How many protons does chlorine have? ___________

The mass number of an element is a whole number equal to the number of protons and neutrons. Every atom

has it’s own mass number.

a. Why aren’t electrons counted in the mass number? ______________________________________

b. How many electrons does C-12 have? ________ B-11? ___________ O-16? __________

IONS

Ions represent atoms that have either gained or lost electrons forming anions and cations. A list of allowable

charges is listed on the top right corner of every element box on the periodic table.

a. Why can’t atoms gain protons to become positive? ______________________________________

b. Why can’t atoms lose protons to become negative? _____________________________________

c. What are negative ions called? __________________

d. What are positive ions called? __________________28


e. A sample has 35 protons and 36 electrons. Give the element symbol and charge. _______

f. A sample has 1 protons and 0 electrons. Give the element symbol and charge. _______

g. A sample has 19 protons and 18 electrons. Give the element symbol and charge. _______

ISOTOPESIsotopes are atoms of the same element with the same number of protons. But they have different number of

neutrons and a different mass.

a. What do isotopes have in common? ___________________________________________________

b. How are isotopes different? __________________________________________________________

c. Which of the following are isotopes? 12

6C 157N 14

6C 157N 12

5B

The atomic mass of an element is the weighted average mass of the naturally occurring isotopes.

a. Explain how mass number and atomic mass are different. __________________________________

____________________________________________________________________________________

b. What the atomic mass of Carbon? ______________

c. If there are two isotopes of carbon, C-12 and C-14, which is more abundant? __________

d. Calculate the atomic mass of a sample of element X which contains 45% X-118 and the rest is X-120.

ELECTRONS, BOHR, AND SPECTRA

Neils Bohr organized the electrons into energy levels. Electrons closer to the nucleus have less energy than

electrons further from the nucleus. The first level holds only 2 electrons. The second level holds 8, third holds

18 and fourth 32. These numbers are reported on the periodic table. Each element’s box has an electron

configuration in the ground state showing how many electrons are in each level.

a. What is the electron configuration of Neon? ________________________

b. What is the electron configuration of Strontium? _________________________

c. Which element has the ground state electron configuration 2-8-9-3? ____________________

d. Draw the Bohr diagram of the following:

29

C-14 S-32 F-19-


The last level contains valence electrons that can be lost or gained to form ions involved in bonding. Cations

are positive ions that have lost electrons, therefore having more positive protons than negative electrons.

Anions are negative ions that have gained electrons and then have fewer protons than electrons.

a. How many valence electrons does Sodium have? ________

b. How many valence electrons does fluorine have? ________

c. If an atom has 8 protons and 10 electrons, what is the charge? _____ What type of ion is it? ______

d. If an atom has 12 protons and 10 electrons, what is the charge? ____ What type of ion is it? ______

e. Draw the lewis diagram of the following:

F S P-3 Na+

When energy is added to the atom, electrons can move up to higher energy levels, in the excited state. The

excited state is unstable. When the electrons return to the ground state they release energy in the form of

light called a spectra. Every atom has a different spectrum.

a. Energy is _____________ when electrons move from higher to lower energy levels.

b. Energy is _____________ when electrons move from lower to higher energy levels.

c. Spectra is observed when electrons move from _________ to __________ energy levels.

d. Why can you identify atoms by their spectra? ___________________________________________

e. Identify which two gases (A, B, C, or D) are in the unknown mixture: _________________________

e. Why are spectra a better identifier than the flame test?

g. How are spectra and flame test similar?

30


31

honors atomic class packet unit 3 - ms. drury's flipped ... · web viewthe sum of the protons...

Documents