1. Parts of an Atom

2. First off, what is an atom?
Atoms are the smallest parts to which an element can be divided yet still be that element.
Atoms are the building blocks of all matter.

3. How small is an atom?
An atom is so small that a penny contains about 2 x 1022 or 20,000,000,000,000,000,000,000 atoms!!!

4. But there’s more…
Atoms consist of even smaller particles. These include:
Protons
Neutrons
Electrons

5. Parts of an Atom
The protons and neutrons make up the center or nucleus.

6. The Nucleus
The center of an atom
Small, dense (packed tightly)
Contains protons and neutrons: most of the atom’s mass
So dense, if it were the size of a grape, it would weigh over 9 million tons!

7. Protons Located in the nucleus Positive charge (+)
Mass of 1 atomic mass unit (amu)
protons = positive

8. Have no charge - neutral Mass of 1 amu
Neutrons
Located in the nucleus
Have no charge - neutral
Mass of 1 amu
neutrons = neutral

9. Electrons Found outside of the nucleus in electron clouds
(think of rings around a target)
Negatively charged (-)
Mass of almost zero
Number of electrons equals the numbers of protons to cancel out the charges
(think of -1+1=0)
electrons = negative

10. Review: Parts of an Atom
Charge
Location
Mass
Proton
Positive (+)
Nucleus
1 amu
Neutron
No charge
Electron
Negative (-)
Electron Clouds
Almost zero