CLASS 5C
Classroom Activities: Chemical Bonding
Objectives
•
Assign an electron dot structure fbr a covalent molecule.
•
Predict the threedimenstonal structure ota covalent molecule given its electron
dot structure.
Overview
Why do substances behave the way they do? I low can a flw dozen different chemical
elements combine to lbrm the incredible variety of materials around us? The key is
hnu/mg. Atoms combine with each other in specific ways to make molecules, much as
sounds combine in specific ways to make meaningful words. in this activity, you will
learn some of the rules for constructing molecules from atoms.
Activity 1:
Electron configurations of ions
Write down the valence electron contigurations of the neutral atoms and ions in the table
be low.
\torn
1
Na
Mg
Valence Configaaration
Ion
Valence Configuration
Na
I
2
Mg
0
O2
F
F
K
,
2f
Ca
Ca
C’s
Cs
Sr
Sr
s
2
s
pyc lflQfl
2f
FMI
2flfl7
PHYS 1 090
BONDING—2
Activity 2: Covalent bonding opportunities
For each atom or ion below, determine the number ot its valence electrons, portion them
as evenly as possible to the tour valence orhtals on a dot diagram, identify the number of
impaired electrons, and predict the number of covalent bonds the atom or ion can make.
Atom or
.
ton
Number of Valence
Hectrous
Dot dtagram
S
S
11
II
13
13
C’
C,
0
0
()
0
Cl
Cl
Cl
Cl
N
N
p
p
Ca
2f
Ca
Unpaired
clectrons
Honds
possible
PHYS 1090
BoNDING3
Activity 3: Covalent molecules
Construct dot diagrams tbr each individual atom and then draw the dot diagram for the
diatomic covalent molecule.
Molecule
Atom diagrams
Molecule diagram
II’
II
H
2
Cl
(1
Cl
lll3r
II
Br
FCI
F
Cl
Cli
Cl
I
Construct the dot diagrams for each individual atom below and then draw the dot diagram
tor the entire polyatomic molecules.
Formula
Atom diagrams
Molecule diagram
4
CH
C
H
4
Cd
C
Cl
1
NH
N
11
CI
2
CH
C
H
Cl
NFI
C
2
I
N
F!
Cl
3
BF
B
F
I
H
3
YS 1090
Activity
BONDING—4
4: MultIple Centers
l)raw legal dot structures corresponding to the molecular tbrmulas given below. Some of
the lbnnulas may he satisfied by more than one structure.
(:1140
6
”
2
C
NH,0
N (two structures)
7
H
2
C
0 (make a structure in which no two oxygen atoms are attached to the same carbon
8
H
3
C
atom)
PHYS 1090
Activity 5: bauble and triple bonds
Begin by drawing structures with single bonds between atoms and then complete the
atoms’ octets by drawing additional bonds between adjacent atoms with unpaired
electrons. II jilts about the structures are given for some ol the cases: von will need to
ligure out a structure in which bonding is satisfied for the other cases. Do not draw any
cyclic molecules! (Cyclic molecules can exist, but multiple-bonded molecules are the
point ot this activity.) It may help to use tiles and beans to keep track of all the electrons.
Cl l() (both hydrogens attach to the carbon)
1 14 (two hydrogens attach to each carbon)
2
C
0 (one hydrogen attaches to the carbon, the other to an oxygen)
2
Cl1
COC 12
N0 (there are several possible structures)
5
H
2
C