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