ChemCatalyst:
HW Due: None
Get your clicker!
Using the data below, calculate the
average atomic mass of silicon.
Isotope
Mass (amu)
Abundance (%)
28 Si
14
27.98
92.21
29 Si
14
28.98
4.70
29.97
3.09
30 Si
14
Today’s Objectives:
1.
3.
Identify the period, group, and block of an element
2. Write an atom's electron configuration
Identify an atom based upon its electron configuration
0%
El
ec
tro
ns
0%
ns
0%
Ne
ut
ro
C.
s
B.
Protons
Neutrons
Electrons
Pr
ot
on
A.

Using the data below, calculate the average atomic
mass of silicon.
Isotope
Mass (amu)
Abundance (%)
28 Si
14
27.98
92.21
29 Si
14
28.98
4.70
29.97
3.09
30 Si
14


(27.98)(0.9221) + (28.98)(0.047) + (29.97)(0.0309)
= 28.09 amu
0%
Cl
o
se
rt
o
m
th
e
as
s
m
as
of
t
he
so
ft
he
iso
...
...
0%
se
rt
o
B.
Closer to the
mass of the
isotope with the
heaviest mass
Closer to mass
of the isotope
with the
greatest
abundance
Cl
o
A.

Using the data below, calculate the average atomic
mass of silicon.
Isotope
Mass (amu)
Abundance (%)
28 Si
14
27.98
92.21
29 Si
14
28.98
4.70
29.97
3.09
30 Si
14


(27.98)(0.9221) + (28.98)(0.047) + (29.97)(0.0309)
= 28.09 amu
0%
0%
0%
18
C.
9
B.
7
9
18
7
A.
0%
0%
0%
18
C.
9
B.
7
9
18
7
A.
0%
7
gr
o
to
in
Fit
Ar
e
gr
ou
up
s
6
ps
8
&
&
7
&
ds
6
pe
r io
0%
9
0%
to
C.
in
B.
Fit into periods
6&7
Are groups 8 &
9
Fit into groups 6
&7
Fit
A.
0%
0%
0%
20
C.
4
B.
2
4
20
2
A.
0%
0%
0%
38
C.
4
B.
2
4
38
2
A.
0%
0%
0%
0%
4
D.
3
C.
2
B.
1
2
3
4
1
A.
0%
0%
0%
0%
9
D.
6
C.
3
B.
1
3
6
9
1
A.
0%
0%
0%
0%
24
D.
12
C.
10
B.
5
10
12
24
5
A.
0%
0%
0%
0%
24
D.
14
C.
10
B.
5
10
14
24
5
A.
0%
0%
0%
Hg
C.
He
B.
H
He
Hg
H
A.
0%
0%
0%
8
C.
4
B.
3
4
8
3
A.
0%
0%
0%
0%
f
D.
d
C.
p
B.
s
p
d
f
s
A.
0%
0%
0%
0%
f
D.
d
C.
p
B.
s
p
d
f
s
A.
0%
0%
0%
0%
9
D.
8
C.
7
B.
6
7
8
9
6
A.
Electrons are found
orbiting the nucleus in a
particular path
0%
In
sid
nu
c le
us
th
e
et
he
nu
c le
us
0%
e
B.
Inside the
nucleus
Outside the
nucleus
Ou
ts
id
A.


Definition: the
arrangement of electrons
in space around a
nucleus
The periodic table reveals
patterns in how the
electrons are arranged


Always start at hydrogen
List the boxes you have to go through to
get to the atom of interest
◦ If you go through multiple boxes that have the
same number/letter use a superscript to indicate
how many of that type of box were passed

You must include the position of the atom
of interest

Be
1s22s2

Add up the
superscripts! What do
you notice?
2 + 2 = 4 = atomic # of Be
Al
1s22s22p63s23p1 2 + 2 + 6 + 2 + 1= 13 = atomic # of Al

I
1s22s22p63s23p64s23d104p65s24d105p5

Pb
1s22s22p63s23p64s23d104p65s24d105p66s24f145d10
6p2
How can you check your
work?

Electron configurations can also be used to
identify an atom
◦ Sum of subscripts = atomic #
◦ Example: 1s22s22p63s23p4
 2 + 2 + 6 + 2 + 4 = 16 = atomic # 16
 Element is S

The last letter/number can be found on
the periodic table
◦ Example:
1s22s22p63s23p64s23d104p65s24d105p66s24f145d9
 Find 5d9
 5d9 = Au
He Fears Clowns!!
He
Cl
Fe
Ar
S
O
W
N
S
er
io
d
15
,d
bl
oc
k
0%
oc
k
bl
4,
p
Gr
o
up
Gr
o
up
4,
p
er
io
d
15
,p
4,
s
pe
r io
d
15
,
up
Gr
o
0%
oc
k
0%
bl
oc
k
bl
4,
p
pe
r io
d
D.
0%
15
,
C.
up
B.
Group 15, period
4, p block
Group 15, period
4, s block
Group 4, period
15, p block
Group 4, period
15, d block
Gr
o
A.
B.
C.
1s22s22p63s23p64s24p5
1s22s22p63s23p64s24d104p5
1s22s22p63s23p64s23d104p5
0%
0%
0%
1s
22
s2
2p
63
s2
3p
64
1s
s2
22
4p
s2
5
2p
63
s2
3p
64
s2
4d
1s
22
1.
..
s2
2p
63
s2
3p
64
s2
3d
1.
..
A.
0%
0%
0%
0%
Cd
D.
Lr
C.
Hg
B.
Lu
Hg
Lr
Cd
Lu
A.

Electron Configurations Review