Chemistry
Chemistry affects just about everything
around us. Scientists use chemical
knowledge to change, improve, or invent
such things as foods, medicines, and
materials of all kinds. They also use
chemistry to understand the world of living
things around us and how the universe
itself functions. Knowing the properties of
elements and compounds is a major goal
of scientists working in the field of
chemistry.
Matter
• Matter
• Matter is everywhere.
• Matter is anything that takes up space
and has mass.
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solids
liquids
gases
plasmas
Energy determines the state!
Element
A substance made up of only one type of
matter
Examples: gold, silver, oxygen
Periodic Table
• Elements listed in a pattern.
Name of the element
Atomic Number =
number of protons
in the nucleus
Gold
79
Au
196.96655
Symbol
Atomic
Weight
Hydrogen
1
H
1.0080
Atoms
• The smallest particles of an element; the
building blocks of matter
Nucleus:
•Protons
positive charge;
equal number of
protons and
electrons
•Neutrons
no electrical
charge; same
mass as
proton
Circling the nucleus:
•Electrons
negative charge;
very light
Molecules
• When atoms combine chemically
• Neutral particles that are formed when
electrons are shared by atoms rather than
being gained or lost
• For example, two pairs of electrons shared
by two hydrogen atoms and an oxygen
atom make a molecule of water
Only the electrons that
are farthest out can be
shared or transferred.
These are called valance
electrons.
H20
Compound
• When two or more different elements
combine chemically.
• The properties of the compound change
from the original elements.
• It can be separated only by chemical
means, not by physical properties.
• Examples:
water, table salt, sugar, rust, YOU!
Our Silly Putty!
Mixture
• One element cannot easily be changed
into another element. A mixture is a way
to combine them.
• A mixture is when two or more types of
matter are combined
• Mixtures can be separated back out into
the two elements through filtering or
evaporation. Examples: salt water and
peas and carrots.