Chemistry Review
What is matter?
…anything that takes up space & has
mass.
EVERYTHING IS MADE OF MATTER!!!
So what is matter made of?
ATOMS!!
What does an atom look like?
…we don’t really know
what atoms “look”
like, but we do know
what they are made
of!
This is just a model-
The 3 subatomic particles of an
atom…
1) Proton: has a + charge, is in the
nucleus.
2) Neutron: has a neutral charge & is
also in the nucleus.
3) Electron: has a – charge and is in the
“electron cloud” around the nucleus,
usually in specific “levels”.
So how do atoms make all this
stuff?
There are over 100 different ELEMENTS.
These elements bond with other atoms,
maybe of different elements or the
same elements, and make
COMPOUNDS.
Compounds act differently then the
atoms they are made of.
Whenever atoms bond or a bond is
broken some energy may be absorbed
& stored or some energy is released.
So what is a compound?
…2 or more atoms that are chemically
bonded.
(Compounds can be created or broken
down chemically, elements can’t be
broken down.)
What are 2 main types of
chemical bonds?
1) Ionic – 1 atom loses electron(s) & 1
atoms gains electron(s)
2) Covalent – the atoms share electrons.
Ionic bond
Sodium loses an electron, chlorine gets those
electrons.
Sodium becomes + charged, chlorine becomes
– charged…and now the “opposites” are
attracted to each other.
Covalent Bond
The oxygen and hydrogen atoms share electrons.
Umm…why are we learning
about chemistry in biology?
Every biological process is part
of a chemical reaction!
All of the energy we need
depends on chemical
reactions!
5 elements make up over 90% of your
body!
C, H, N, O, P
(Carbon, Hydrogen, Nitrogen, Oxygen,
Phosphorous)
What about pH stuff?
pH is the measure of the amount of
hydrogen ions (H+) in a solution.
Lots of H+ makes a solution acidic.
Lots of OH- (hydroxide ions) makes a
solution basic (or alkaline)
What about acids?
They have a pH between 0 & 6 on the pH
scale.
They taste sour.
They are corrosive (especially the really
acidic things).
What about bases?
They have a pH between 8 & 14 on the pH
scale.
They taste bitter & are slippery.
They are also corrosive…especially the
really basic ones!
What is 7 on the pH scale?
7 = neutral…pure water is an example.
Why is pH important in biology?
Many of the chemical reactions that take
place can only occur at certain pH’s.
Also some things in the environment are
damaged by pH changes.
The pH scale