SNC2P Worksheet!
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Bohr Model Electron Shell Diagrams!
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Electrons exist in shells at specific energy levels. Each shell can hold only a certain number of electrons and each shell must be
filled before electrons are placed into the next outer shell. For the first 20 elements:
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•! The first (inner shell) can hold up to 2 electrons.
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•! The second shell can hold up to 8 electrons.
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•! The third shell can hold up to 8 electrons.
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•! The fourth shell can hold 2 electrons.
On the simplified periodic table below, draw the electron shell (Bohr) diagrams for the first 20 elements.
1
1
4
2
H
7
3
Li
9
4
Be
23
11
Na
24
12
Mg
39
19
K
40
20
Ca
11
5
B
27
13
Al
He
12
6
C
14
7
N
16
8
O
19
9
F
20
10
Ne
28
14
Si
31
15
P
32
16
S
35
17
Cl
40
18
Ar
Elements appearing in the same column of the periodic are considered as being in a “family” (eg. those in the first column are
the “Alkali Metal” family).
a)!With respect to the electron arrangements in the electron shells, how are the elements in each family similar?
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b)!How are they different?
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