Representing Atoms Visually

Bohr Models
Atomic Structure Review
 Protons = positive charge; atomic number
 Neutrons = neutral; atomic mass
(rounded) – atomic number

protons and neutrons are located in the nucleus
 Electrons = negative charge; same as #
protons in a neutral atom


Electrons are located in shells, energy levels or
orbitals surrounding the nucleus.
Each shell/level/orbital holds a specific number of
electrons
What are Bohr models?
 One type of visual representation of an
atom
 There are three things that you need to
have:
 Number
of shells (period #)
 Number of valence electrons (group #)
 Total number of electrons
How do I draw a Bohr model?
Determine the number of electrons, protons, &
neutrons from the atomic number and atomic
mass.
2. Draw a little circle for the nucleus and label inside
with the number of protons and neutrons
1. p+ = protons, n0 = neutrons
3. Determine the number of energy levels from the
period that the element is in. Draw larger circles
around the nucleus for each energy level.
4. Place dots representing the electrons in each
energy level on these circles, according to how
many each level can hold.
1.
Using the PT for Bohr models
 Each period represents an energy level
 Each squarer (element) represents an
electron

NOTE: Each period has a certain number of
squares (electrons). This will tell you how many
electrons each level can hold.
Energy Level
Electrons Allowed
1
2
2
8
3
8
1
1
18
2
2
3
4
14 15 16
Period 1 = 1 Electron13Shell
Period 2 = 2 Electron Shells
Period
3 =Metals
3 Electron Shells
Transition
Period 4 =
Period 5 =
Period 6 =
Period 7 =
5
6
7
6
7
4 Electron Shells
5 Electron Shells
6 Electron Shells
7 Electron Shell
Period 6 = 6 Electron Shells
Period 7 = 7 Electron Shells
17
3 Valence Electron
4 Valence Electron
5 Valence Electron
6 Valence Electron
7 Valence Electron
8 Valence Electron
1 Valence Electron
2 Valence Electron
Example of a Bohr model
 Chlorine
Bohr Practice
Argon (Ar)
Oxygen (O)
8
8
2
Neon (Ne)
Silicon (Si)
Phosphorus (P)
1 per
2 per
3 per
Which
element is
this?
Helium
Argon
Beryllium
Barium
Boron
MAG-NE-SIUM
Classwork/Homework
 Complete your worksheet on Bohr
models (both sides)
 Due T 10/25/11