1. The Structure of the Atom

2. Standard Atomic Notation (for a neutral atom)
Atomic number
Atomic symbol 35 Br 80
Mass number
# of protons = Atomic number = 35 p+
# of electrons = Atomic number = 35 e-
# of neutrons = Mass number – Atomic number
= = 45 n0

3. The Bohr-Rutherford Model
Nucleus
contains protons and neutrons
Orbits
electrons circle the nucleus in orbits
each electron orbit has a definite or maximum amount of electrons.
the first orbit has two electrons, the second orbit holds eight electrons, and the third orbit holds no more than eight electrons. 2
Helium Atom
2 positive protons in nucleus
2 neutral neutrons in nucleus
2 negatively charged electrons in the first energy level He 4

4. How to Draw a Bohr-Rutherford Diagram14 Si
14 electrons and
14 protons 28
Nucleus
use the atomic number to determine the protons
subtract the mass number and atomic number to determine the neutrons
Draw in the energy levels
- row # = # orbits
Add electrons following the pattern for the first 20 elements
28-14 = 14 neutrons
14 p
14 n
Mr. Dee Video Clip: Periodic Table