Course material

1. Answers: Question 1 Question 2 The periodic table is not
Answers:
Question 1
Question 2
The periodic table is not rectangle since the arrangement of the elements has been done
based on the orbitals that fill their inner shells and orbits including s, p, d and f have varying
electronic configurations
Question 3: Electronic Configurations
Atom
No of electrons
Electron configuration
Hydrogen
1

2. 1
Helium
2
2
Lithium
3
2.1
Beryllium
4
2.2

3. Boron
5
2.3
Carbon
6
2.4
Nitrogen
7
2.5
Oxygen

4. 8
2.6
Fluorine
9
2.7
Neon
10
2.8
Sodium
11

5. 2.8.1
Magnesium
12
2.8.2
Aluminium
13
2.8.3
Silicon
14
2.8.4

6. Phosphorus
15
2.8.5
Sulphur
16
2.8.6
Chlorine
17
2.8.7
Argon

7. 18
2.8.8
Potassium
19
2.8.8.1
Calcium
20
2.8.8.2
Ionic configuration
Ca2+: 2.8.8
Famous half-filled/fully filled subshells

8. Ra: [Rn] 7s2
[Ar] 3d5 4s1
[Ar] 3d10 4s1
[Xe] 4f14 5d10 6s1
Question 4
Graphene is turning out to be one of the most sought after nanomaterials owing to its
unique combination of outstanding features. Graphene is a conductor of electricity since it is
made up of delocalized electrons that freely move across the surface.
Question 5
The intermolecular forces holding the particles of carbon dioxide together strengthen at -
80 resulting in the particles being pulled much closer to one another and hence formation of
a solid. CO2 tends to be soluble due to the fact that the molecules of water get attracted to
the polar regions. The bod between oxygen and carbon is not polar as the one between
oxygen and hydrogen even though it is adequately polar to enable dissolution of carbon
dioxide in water.
Question 6
Ionic bond>covalent bond>hydrogen bond>permanent dipole bond>transient dipole bond
Question 7
Geckos adhere to the ceilings and walls using numerous microscopic hairs on their feet due
to van der Waals forces. Since van der Waals forces tend to be of quite short range, the hairs
of gecko must come very close to the surface to abide by the use of the mechanism. The
interaction between the tiny hairs with the vertical surface is by Van der Waals forces.
Question 8
The forces holding the molecules of liquid water is hydrogen bonds. Oils do not have polar
regions and hence dissolving would require breakage of some of the hydrogen bonds of
water. The bonds will not be broken and as such the oil remains to be immiscible.
Question 9
Sodium metal, just like all the other metals, is a good conductor of electricity since it has
free delocalized electrons which are able to move hence electricity are able to pass through.

9. Solid sodium chloride on the other hand does not conduct electricity since it does not have
electrons that can freely move around. In molten state, sodium chloride experiences
electrolysis, which incorporates the conduction of electricity due to the movement as well
as discharge of ions.
Question 10
Tetrachloromethane (CF4) exerts a very strong pull especially on the shared electrons
resulting in the creation of regions with high electron density about itself. As such, the same
negative fluorine in a single molecule repel the same negative fluorine in another molecule
and CF4 molecules goes into phase at an unanticipated low temperature.