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 10 22 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. 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 PartsChargeLocationMass Proton Positive (+)Nucleus1 amu Neutron No chargeNucleus1 amu Electron Negative (-)Electron Clouds Almost zero