What is Chemistry?

Learning Objectives

What is chemistry?What are the building blocks of

matter?How does matter interact?How is matter organized?

What is Chemistry?

The study of the composition of matter and the changes that matter undergoes

It affects all aspects of life and non-living objects too

Chemistry explains things that we observe in the world around us

For example: the changing of the leaves in fall

Matter

Is anything that has mass and occupies space

It doesn’t have to be visible For example: humans, air, water, your

table & plants What isn’t matter? Light, heat, sound, electricity &

gravity

Phases of Matter

Three main phases: Solid Liquid Gas

What is the 4th state of matter and where is it found?

Elements

Are the simplest form of matter 114 elements have been identified Different elements combine to form

compounds

The Periodic Table

Periodic Table

Atom

Is the simplest particle of an element that retains all the properties of that element

They are too small to observe directly

So we use a model

Atom Model

The Nucleus

Located in the middle of an atom Made up of 2 subatomic particles:

Protons-have a positive charge

Neutrons-have no charge

Atomic Number, Atomic Mass,& Mass Number

The number of protons in an atom determines the atomic number of the element

The atomic mass is the average mass of the atoms in the element

The mass number an atom is the total number of protons & neutrons

Electrons

Balance out the number of protons with negative charges

They are very high energy and have very little mass

They are found in orbitals around the nucleus

The farther away from the nucleus, the more energy an electron has

Compounds

A compound is a substance made of two or more different elements that are chemically bonded

Compounds are unique A chemical formula shows the kinds and

proportions of atoms of each element in the compound

For example: Fe2O3

2 iron atoms and 3 oxygen atoms

How many of each?

C8H10N4O2

C3H8O

KMnO4

CaCl2

H2O

NaCl

Molecules

A molecule: is the simplest part of a substance that retains all of the properties of the substance and can exist in a free site

Some molecules are composed of atoms of different elements

Some molecules are composed of atoms of the same element

Diatomic Molecules

Are molecules composed of atoms of the same element

Examples: Hydrogen, Iodine, Bromine, Oxygen, Nitrogen, Chlorine, & Fluorine

HI BrONClF

Pure Substances & Mixtures

Pure Substance: is matter that has a fixed composition and definite properties

Examples: Elements & Compounds Mixture: is a combination of 2 or more

substances that are NOT chemically combined

Examples: Air & Grape Juice

Mixtures

Can be separated They are formed by mixing pure

substances They have properties similar to the

pure substances that make them up Mixtures are classified by how well

they are mixed

Types of Mixtures

Heterogeneous: substances in which components are NOT distributed evenlyExamples: flour & water, sand & salt

Homogeneous: substances in which the components are evenly distributedExamples: Pop, sugar & water

Miscible: A homogeneous mixture of liquidsExample: Gasoline

Immiscible: A heterogeneous mixture of liquidsExample: Oil & Water