Download 3-4 Bohr and Lewis

Name:
Period:
Date:
Draw the Bohr Model
Follow the 2, 8, 8 , 8, 8, 8….Rule to determine if the element is Happy or Unhappy (Stable or Unstable)
An atom is always neutral. It has no net charge. Every carbon atom has 6 protons, it must have 6
electrons. Electrons in an atom are arranged in energy levels (or shells) around the nucleus. The electrons
in the 3rd energy level have more energy than electrons in the first energy level. The maximum number of
electrons in the first energy level (shell) is 2. The maximum number of electrons in the second energy
level (shell) is 8. The outermost energy level (shell) can never have more than 8 electrons in it. These
electrons in the outermost energy level (shell) are called valence electrons.
Atomic # = # Protons
Also
Atomic # = # Electrons
Atomic Mass = #Protons + #Neutrons
So
# Neutrons = Atomic Mass - # Protons
First step: Determine the number of protons, neutrons and electrons in each element.
Second step: Represent the nucleus as a small circle and indicate the number of protons and neutrons.
Third step: Making larger circles, arrange the electrons around the nucleus.
H
Atomic #
1
H
1.01
He
1e1 p+
0 nΦ
Atomic
Mass
Unhappy
Be
C
Na
Si
Lewis Structures
Name:
Lewis structures, or dot diagrams, are a simplified way to show how the valence electrons are arranged in the outer shell. This is
where the chemical reactions take place. Atoms will either share or give away these electrons to form bonds.
Using your periodic table, determine the number of valence electrons for each element.
Draw a dot to represent each valence electron around the element symbol.
Follow the pattern below starting with position number 1.
6
3
7
H
Examples:
2
Xe
1
5
Ba
In
Se
He
8 4
Li
Be
B
C
N
O
F
Ne
Na
Mg
Al
Si
P
S
Cl
Ar
K
Ca
www.middleschoolscience.com 2008