Welcome !!!!

• Dr. Leslie Sombers leslie_sombers@ncsu.edu

• Leyda Lugo-Morales lzlugomo@ncsu.edu

http://moodle.wolfware.ncsu.edu

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Today we will:

· Develop a definition for Chemistry.· Gain an understanding of where Chemistry, matter and Physical and Chemical change spiral throughout the curriculum.

Welcome !!!!

A. Develop a thinking map or brainstorm a list to show what you know about Chemistry.

B. Share your map with your group/neighbor.

C. Place your map on the wall.

D. With your group, develop a definition for chemistry. Write it on your sentence strip and post it for others to see.

Your assignment:

What is Chemistry?

• The study of all substances and the CHANGES they undergo.

• Referred to as the Central Science because it overlaps so many other sciences.

• It all begins with curiosity!

Copyright © Houghton Mifflin Company.All rights reserved. Presentation of Lecture Outlines, 2–5

Pre- test

To assess content knowledge and learning…..Sorry guys, it’s a requirement!!!!

Re-organize and Brainstorm

A. Develop new groups. The groups should contain folks from different areas and grade levels. (No one in the same group should have the

same colored dot)

B. With your new group, brainstorm what is meant by physical and

chemical changes.

Physical Changes

• Physical change alters the substance without changing its composition or chemical identity.

• Boil, melt, cut, break, split, grind, crush, bend, condense, freeze, dissolve and crack are examples of physical changes.

Physical Properties

• A physical property is a condition that can be measured or observed without changing the identity of the substance.

Examples of physical properties include color, solubility, odor, hardness, density, melting point and boiling point, etc.

Chemical Properties

The ability of a substance to undergo a chemical reaction to form a new substance is called a chemical property. Chemical properties are observed when a substance undergoes a chemical change.

Chemical Change

• A change in which one or more substances are converted into different substances is called a chemical change or chemical reaction.

C + O2 CO2

(reactants) (product)

Look for terms such as . . .

• burn • rot• rust• decompose • ferment • explode • oxidize • corrode • grow • precipitate• gas formation• digest

Combustion – powering the space shuttle

Brainstorm

What is meant by a mixture, a solution?

Classifying Matter

• Matter is classified by the number of phases it contains.

• Any part of a system with uniform composition and properties is called a phase.

• Matter can be classified as either Homogeneous or Heterogeneous.

Homogeneous & Heterogeneous

Homo = same Hetero = different

•Homogeneous materials exist in only one phase.

•Heterogeneous materials contain more than one phase.

•Includes solutions, compound & elements

•Heterogeneous materials are all mixtures

Online Solution Basics….

Mixtures

• Mixtures are a physical blend of 2 or more kinds of matter.

• Mixtures can be either homogeneous (solutions) or heterogeneous.

• Separation of mixtures is done by physical means such as magnets, distillation, chromatography and filtration.

Mixture activity… Separating a solution…

Online mixture examples

Pure Substances

•A pure substance has a fixed composition . Elements and compounds are pure substances.

•Unlike mixtures, every sample of a pure substance has exactly the same characteristic properties and composition.

Elements and Compounds

An element is a collection of the same type of atom. They are the simplest form of matter that can exist under normal lab conditions.

Compounds consist of two or more elements that are chemically combined. They can be separated only by a chemical change.

Making a compound….

Extensive vs. Intensive

Extensive Properties

• Depend on the amount of matter present

• Mass, volume, length, height, amount of energy, etc.

Intensive Properties

• Do not depend on the amount of matter present

• Density, boiling point, melting point, color, ability to conduct electricity, etc.

• Density is defined as the mass in a unit of volume.

Density

• In the SI unit system, mass is measured in kg and volume is measured in m3, thus, the unit of density is kg/m3 (kilogram per cubic meter). But this is inconvenient for most substances, therefore, g/cm3 (gram per cubic centimeter) is a more common unit of density.

Unit of Density

• Density is a characteristic property of matter. We can differentiate substances by using their densities.

Examples:

How to manipulate the formula

In order to calculate the density of an object, first we measure its mass with a scale, then we find its volume by measuring it with a ruler, if it has a regular shape. Otherwise we use the graduated cylinder method for irregular objects, and liquids. Then, by dividing mass by volume, we find the density of the object.

How can we calculate the density of an object?

What is the volume of 24 tons of cement? (dcement = 3000 kg/m3)

Calculate the mass of copper having the same volume as 31,5 g of silver. Use Table 1.7.

Density Activities

When it comes to atoms and molecules, small takes on a whole new meaning. If you had 18 mL of water (little more than one tablespoon), and you could count all of the H2O molecules at a rate of one million per second, it would take you 190 million centuries to count them all!!!

Standard Metric Prefixes

Metric System & Scientific Notation

Metric System

• The metric system is based on a base unit that corresponds to a certain kind of measurement

• Length = meter• Volume = liter• Weight (Mass) = gram

• Prefixes plus base units make up the metric system – Example:

• Centi + meter = Centimeter• Kilo + liter = Kiloliter

Metric System

• The three prefixes that we will use the most are:– Kilo= 1000– centi = 1/100 (one hundredth)– milli= 1/1000 (one thousandth)

• How do you remember all of them?• Kissing Hairy Dark space dogs causes

mono

Kilo(1000)

Hecto(100)

Deca(10)

Base Units

metergramliter

deci(1/10)

centi(1/100)

milli(1/1000)

Metric System

• So if you needed to measure length you would choose meter as your base unit– Length of a tree branch

• 1.5 meters – Length of a room

• 5 meters • But what if you need to measure a longer distance, like from

your house to school?– Let’s say you live approximately 10 miles from school

• 10 miles = 16093 meters – 16093 is a big number, but what if you could add a prefix

onto the base unit to make it easier to manage:• 16093 meters = 16.093 kilometers (or 16.1 if rounded to

1 decimal place)

Typical Metric Units

• What metric unit would you use to measure the length of the room?

• What metric unit would you use to measure the distance between the mall and school?

• What metric unit would you use to measure your weight?

• What metric unit would you use to measure the amount of liquid in a soda bottle?

• What unit would you use to measure the amount of liquid in an eye dropper?

Metric System

• These prefixes are based on powers of 10. What does this mean?– From each prefix every “step” is either:

• 10 times larger or

• 10 times smaller– For example

• Centimeters are 10 times larger than millimeters• 1 centimeter = 10 millimeters

Kilo(1000)

Hecto(100)

Deca(10)

Base Units

metergramliter

deci(1/10)

centi(1/100)

milli(1/1000)

Metric System

– Centimeters are 10 times larger than millimeters so it takes more millimeters for the same length

1 centimeter = 10 millimeters

Example not to scale

1 mm

1 mm

1 mm

1 mm

1 mm

1 mm

1 mm

1 mm

1 mm

1 mm

1 cm

40

41

41

40

Metric System• For each “step” to right,

you are multiplying by 10

• For example, let’s go from a base unit to centi

1 liter = 10 deciliters = 100 centiliters

2 grams = 20 decigrams = 200 centigrams

( 1 x 10 = 10) = (10 x 10 = 100)

(2 x 10 = 20) = (20 x 10 = 200)

Kilo(1000)

Hecto(100)

Deca(10)

Base Units

metergramliter

deci(1/10)

centi(1/100)

milli(1/1000)

Kilo(1000)

Hecto(100)

Deca(10)

Base Units

metergramliter

deci(1/10)

centi(1/100)

milli(1/1000)

Metric System

• An easy way to move within the metric system is by moving the decimal point one place for each “step” desired

Example: change meters to centimeters

1 meter = 10 decimeters = 100 centimetersor

1.00 meter = 10.0 decimeters = 100. centimeters

Kilo(1000)

Hecto(100)

Deca(10)

Base Units

metergramliter

deci(1/10)

centi(1/100)

milli(1/1000)

Metric System

• Now let’s try our previous example from meters to kilometers:16093 meters = 1609.3 decameters = 160.93

hectometers = 16.093 kilometers

• So for every “step” from the base unit to kilo, we moved the decimal 1 place to the left (the same direction as in the diagram below)

Kilo(1000)

Hecto(100)

Deca(10)

Base Units

metergramliter

deci(1/10)

centi(1/100)

milli(1/1000)

Metric System

• If you move to the left in the diagram, move the decimal to the left

• If you move to the right in the diagram, move the decimal to the right

Kilo(1000)

Hecto(100)

Deca(10)

Base Units

metergramliter

deci(1/10)

centi(1/100)

milli(1/1000)

Metric System

• Now let’s start from centimeters and convert to kilometers

400000 centimeters = ? kilometers

Kilo(1000)

Hecto(100)

Deca(10)

Base Units

metergramliter

deci(1/10)

centi(1/100)

milli(1/1000)

Kilo(1000)

Hecto(100)

Deca(10)

Base Units

metergramliter

deci(1/10)

centi(1/100)

milli(1/1000)

Metric System• Now let’s start from meters and convert to centimeters

5 meters = ? centimeters

• Now let’s start from kilometers and convert to meters

.3 kilometers = ? meters

Metric System

• Summary– Base units in the metric system are meter, liter, gram– Metric system is based on powers of 10– For conversions within the metric system, each “step” is

1 decimal place to the right or left– Using the diagram below, converting to the right, moves

the decimal to the right and vice versa

Kilo(1000)

Hecto(100)

Deca(10)

Base Units

metergramliter

deci(1/10)

centi(1/100)

milli(1/1000)

Scientific Notation

• Scientific notation is a way of expressing really big numbers or really small numbers.

• For very large and very small numbers, scientific notation is more concise.

• Scientific Notation always has two parts:– A number between 1 and 9.9999…– A power of 10

N x 10x

Writing Scientific Notation

• Place the decimal point so that there is one non-zero digit to the left of the decimal point.

• Count the number of decimal places the decimal point has “moved” from the original number. This will be the exponent on the 10.

• If the original number was less than 1, then the exponent is negative. If the original number was greater than 1, then the exponent is positive.

• Example:– Given: 289,800,000– Start with: 2.898 – Decimal needs to move 8 places to the right– Answer: 2.898 x 108

Try this:

• Given: 0.000567• Start with:• Decimal needs to move:• Answer:

Change Scientific Notation back to Standard Form

• Simply move the decimal point to the right for positive exponent 10.

• Move the decimal point to the left for negative exponent 10.

(Use zeros to fill in places.)• Example:• Given: 5.093 x 106

• Move: 6 places to the right (positive)• Answer: 5,093,000

Try This:

• Given: 1.976 x 10-4

• Move:• Answer:

Copyright © Houghton Mifflin Company.All rights reserved. Presentation of Lecture Outlines, 2–47

Standard Metric Prefixes for the SI Units

How does a study of Physical and Chemical Changes fit into your curriculum?

What are some misconceptions students often have about matter? How will the activities provided help address them?

• Developed a definition for Chemistry.· Gained an understanding of where the major Chemistry strands regarding matter, and chemical and physical change spiral throughout the curriculum.• Discussed mixtures, solution and compounds, density and standard prefixes for SI Units

Today we have: