MIDTERM REVIEWChemistry

CHAPTER 1THE SCIENCE OF CHEMISTRYPG 4-9

Chemistry – the study of matter and how it interacts with other matter

Chemical – any substance that has a definite composition. A chemical is always made of the same “stuff”

no matter where it comes from

EXAMPLES OF CHEMICALS

CHEMICALS

Not all chemicals are bad.

Chemicals are necessary for every day life.

STATES OF MATTER

Three states of matter: Solid Liquid Gas

SOLIDS

Have a fixed volume and definite shape.

Atoms are held tightly in rigid structure and vibrate only slightly

LIQUIDS

Have a fixed volume and indefinite shape

Can easily take the shape if its container

GASES

Indefinite volume and indefinite shape

Atoms are held very loosely together

PRODUCTS VS REACTANTS

Products are what come out of a reaction

Reactants are what are put into the reaction

REACTANTS: H2 AND N2

PRODUCT: NH3

DESCRIBING MATTERSECTION 2PG 10 -19

Matter - anything that has mass and volume

List of non-matter: Time Sound Sunlight Thoughts Gravity Microwaves Heat Memories Reflections Energy

VOLUME VS MASS

Volume – is the amount of space an object takes up

Mass – the amount of matter in an object

https://www.youtube.com/watch?v=kWpgynOgkVE

VOLUME VS MASS

Volume is measured in liters, gallons, or some unit cubed (cm3, m3, in3)

Mass is measured in grams

MEASURING VOLUME

Fill a graduated cylinder and read the lines.

The lines measure mL

Just like the lines on a ruler measure cm

WHAT IS THE VOLUME OF THIS LIQUID?

WHAT IS THE MASS OF THIS LIQUID?

DETERMINING MASS

Mass is measured in grams.

To find the mass of something, you must you a scale or balance.

MASS VS WEIGHT

Weight is the force produced by gravity acting on a mass.

The mass of an object never changes.

Weight varies depending on gravity.

DENSITY

Density – is the ratio of mass to volume of an object.

How much “stuff” is in an object compared to how much space it takes up.

Density = Mass/Volume

DENSITY

Density can be used to identify substances

Every pure element has a specific density that does not change

SECTION 3HOW IS MATTER CLASSIFIED?PG 21 -28

Atoms – the smallest unit of an element that maintains the properties of that element

PURE SUBSTANCE

Pure substances are either elements or compounds.

Pure substances have definite chemical and physical properties

ELEMENTS

Are substances that cannot be broken down into anything else.

Composed of only one type of atom

COMPOUNDS

Composed of more than one type of atom.

Still have definite properties.

Examples : H2O CO2

C12H6O12

MIXTURES

Do not have definite compositions or definite properties

Examples: Salt Water Sand Sugar Water

HETEROGENEOUS VS HOMOGENEOUS

Homogeneous – mixture is distributed uniformly throughout

Heterogeneous – mixture is not distributed uniformly throughout