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

H2 O

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 evenly
 Examples: flour & water, sand & salt
 Homogeneous: substances in which the
components are evenly distributed
 Examples: Pop, sugar & water
 Miscible: A homogeneous mixture of liquids
 Example: Gasoline
 Immiscible: A heterogeneous mixture of liquids
 Example: Oil & Water
