Download Bohr-Rutherford Lewis Dot Diagrams Worksheet

The Structure of Atoms
Bohr-Rutherford Diagrams
Bohr-Rutherford diagrams are one model that describes what an atom looks like. Consider the atom of lithium. What does the BohrRutherford diagram look like?
Step 1:
Using the periodic table, calculate the number of protons, neutrons and electrons.
Atomic number
3
Li
Lithium
6.941
Atomic mass
For lithium: atomic number = 3
atomic mass = 6.941  7 (round to closest whole number)
Therefore:
# protons = atomic number = 3
# neutrons = n = atomic mass – atomic number = 4
# electrons = # protons = 3
Step 2:
Draw the nucleus by first writing the symbol of the element and indicating the number of protons (p) and neutrons (n).
Step 3:
Draw the electrons in their orbits. Only a certain number of electrons can be held in each orbit:
- fill the lower orbits (or energy levels) first
- the first orbit will hold up to two electrons.
- the other orbits can hold up to eight electrons.
- these rules hold up to calcium (element 20)
Examples of Bohr-Rutherford Diagrams:
Carbon:
# protons = atomic number =
# neutrons = atomic mass – atomic number =
# electrons = # protons =
Aluminum: # protons = atomic number =
# neutrons = atomic mass – atomic number =
# electrons = # protons =
Lewis Dot Diagrams
- a Lewis dot diagram is a short form diagram which shows only the “relevant” electrons (the VALENCE eletrons)
- the number of valence electrons corresponds to the group to which the element belongs
- the element symbol is drawn and “dots” around the symbol are drawn to represent the number of valence electrons
Examples:
Sodium
Carbon
Aluminum
Barium
Bromine
Argon
BOHR-RUTHERFORD/LEWIS DIAGRAMS
1
H
3
Li
4
11
Na
12
Mg
19
K
20
Ca
Be 5
13
B 6
Al
14
C
7
N
8
O
9
Si
15
P
16
S
17
2
He
F
10
Ne
Cl
18
Ar