1. Atomic Structure
Chemistry

2. Electrons
Negatively charged subatomic particles. They live on the outside of the nucleus and move constantly. They weigh almost nothing. They are responsible for the chemical properties of the atom.

3. Protons
They are positively charged particles. They live inside the nucleus. They have weight. They are responsible for the atom identity.

4. Neutrons
They are particles with no charge. They live inside the nucleus. They have weight. They are responsible for radioactivity.

6. Atomic Number Number of protons in the atom Mass Number Number of protons and neutrons in the atom

7. What is the atomic number and mass number of:
Carbon
Gold
Sulfur
Oxygen

8. Isotopes
Same number of protons – different number of neutrons. You indicate an isotope by writing the new mass number. Ex: Carbon-14

9. Oxygen-16 Oxygen-17 Oxygen-18
Write the chemical symbol for the following isotopes:
Oxygen-16
Oxygen-17
Oxygen-18

10. Atomic Mass Unit (amu)
One-twelfth of a carbon atom The atomic mass is a weighted average mass of the atoms in a naturally occurring sample of the element. Ex: Carbon 98.89% is C-12, 1.11% is C (.9889) + 13 (.0111) = amu