Chemistry: Unit 1 Module 2 - What is Chemistry

What is Chemistry?

Unit 1 Lesson 2

​Physical Sciences

​Chemistry-and Physics

Physics is the study of energy and motion.

​Physical Sciences

​Chemistry-and Physics

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​Chemistry can be defined as the study of matter and all of it’s interactions.

​But What is Matter then?

​Basically Matter is defined as anything that has MASS and takes up SPACE.

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​But I think it is sometimes easier to describe what isn't matter

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​​Everything is matter except for ENERGY. I.E. Heat, Light, Electricity.

​So what is Mass and how is it different from weight?

Takes up Space?

​Besides mass matter all takes up some sort of space.

​This space is defined as the volume of matter.

​We will measure volume in several different ways but it is simply a measure of the space occupied by a from of matter.

Multiple Choice

Which of these would be a measure of mass?

• 10 meters

• 10 grams

• 10 pounds

• 10 seconds

Multiple Choice

Chemistry is often defined as the study of __________.

• Matter

• Energy

• Magic

• Motion

In chemistry we strive to identify matter and separate it by it's properties.

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​Chemistry Measurements

​Properties can be sorted into two categories.

Intensive - Don't change based on amount

Extensive - Do change based on amount

Intensive properties are very important for separating matter or classifying it. In chemistry one of the most common intensive properties used is Density.

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​Chemistry Measurements

​Properties can be sorted into two categories.

Intensive - Don't change based on amount

Extensive - Do change based on amount

Density is the ratio of a substances mass to it's volume. Two very common measurements taken in a chemistry lab.

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​Chemistry Measurements

Density is intensive because the ratio stays the same no matter how much or how little of a substance you have.

Density is commonly used to separate substances that look very similar.

​Chemistry Measurements

A gold sluice can separate the gold from sand because of it's very high density.

Multiple Choice

The volume of a candy bar is 55cm3.The mass of the candy bar is 70g. What is the density of the candy bar?

• 2.3g/cm3

• 3850g/cm3

• .8g/cm3

• 1.3g/cm3

Multiple Choice

Calculate the density of the cube.

• 2 g/cm³

• 4 g/cm³

• 6 g/cm³

• 8 g/cm³

Multiple Choice

Show all your work on your answer document. D=m/v

• 0.33 g/cm³

• 15 g/cm³

• 3 g/cm³

• 9 g/cm³

Multiple Choice

An irregularly shaped piece of gold was lowered into a graduated cylinder holding a volume of water equal to 17 ml. The height of the water rose to 20 ml. If the mass of the gold was 27 g, what was its density?

• 9 g/mL

• 10.5 g/mL

• 6.5 g/mL

• 8 g/mL

Properties and Changes of Matter​

​Properties of Matter

​In order to classify matter we have to be able to identify properties of matter.

These properties can be measured with our senses or with chemical processes and equipment.

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​Physical Properties

• Anything you can observe about an object or substance without changing the substance which makes it up.

• Examples: Density, shape, size, color, magnetism, melting and boiling point

​Physical Properties

• Physical Properties can be Qualitative or Quantitative.

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• Qualitative properties are described without using numbers or value. They describe the quality of the sample.

​Physical Properties

• Physical Properties can be Qualitative or Quantitative.

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• Quantitative properties are described by using numbers or value. They measure some quantity of the sample.

​Physical Changes

• Physical changes are those changes which do not change the composition of the substance only the shape or state.

  The most commonly mistaken are phase changes. Boiling water till it evaporates is only a physical change.

Chemical Properties

• Chemical properties are those properties which indicate whether a substance will undergo specific chemical processes.

  Examples: Flammability, reactivity with acids or bases or combustibility.

Chemical Changes

• Any change that can change the composition of the substance.

• Since we can't see the composition of the substance we look for common evidence of a chemical change.

Chemical Changes

Evidence a chemical change has occurred:

• ​Production of gas - smoke, bubbles, odor

• Production of light - flames, sparks, glow sticks

• Change in temperature - hot or cold without added source

• Formation of a precipitate - a solid forms when two liquids are mixed

• Change in color - color is not added but is result of reaction

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Multiple Select

Which of the following is an intensive property?

• Freezing Point

• Mass

• Color

• Length

• Volume

Multiple Choice

An ice cream cone melts in a kid's hand while walking outside on a hot summer day. What is this an example of?

• Physical property

• Chemical property

• Physical change

• Chemical change

Multiple Choice

Water boils at 100˚C. What is this an example of?

• Physical property

• Chemical property

• Physical change

• Chemical change