CHEM 3.4 Questions
Exercises
1
Enter the electrons in the correct sub-levels and orbitals.
1s
2s
2p
3s
3p
Nitrogen
Phosphorus
Sodium
Argon
2
Write the electron configuration in s, p, d form for the following atoms and ions.
a) Be
b) O
c) Mg
d) Fe
e) Cu
f) Cr
g) Cl-
h) Mn2+
h) Cu2+
i) Al3+
j) Zn2+
k) Ge
3
a) HCl
Use inter-molecular bonding to explain the difference in melting points for the following.
and
HBr
b) HCl
and
F2
c) HCl
and
HF
CHEM 3.4 Questions
4
Work out the type of intra-molecular bonding in each sample using the table below.
Property
Hardness
Melting point
Solubility in water
Solubility in cyclohexane
Conductivity of solid
Conductivity when
molten
Type of solid
Sample 1
—
low
—
yes
no
—
Sample 2
malleable
high
—
—
yes
—
Sample 3
hard
high
—
—
—
no
Sample 4
—
—
yes
no
—
yes
Sample 5
—
moderate
yes
—
no
—
5
Would you classify the following molecules as pure covalent, polar covalent or ionic?
Use the scale above
a) CH4
b) HCl
c) H2
d) H20
e) F2
f) NaCl
g) CO
h) NO2
i) FeCl2
j) CCl4
k) Al2O3
l) O2
CHEM 3.4 Questions
6
Would you classify the following molecules as pure covalent, polar covalent or ionic?
a) Why does aluminium have a bigger atomic radius than fluorine?
b) Why does sulfur have a bigger atomic radius than oxygen?
c) Why is the atomic radius of Mg2+ smaller than Mg?
d) Why is the atomic radius of O2- bigger than O?
e) How is the atomic radius measured?
8
Would you classify the following molecules as pure covalent, polar covalent or ionic?
a) Draw the equation for the 1st ionization of one mole of gaseous oxygen?
b) Whys does F have a higher 1st ionization energy than oxygen??
c) Why does Na have a lower 1st ionization energy than Li?
d) Why is the 1st ionization energy of N higher than oxygen??
e) Why is ionization energy always endothermic?
CHEM 3.4 Questions
9
Answer the following questions.
a) What is the most electronegative element?
b) Why is oxygen more electronegative then nitrogen?
c) Why is fluorine more electronegative than chlorine?
10
Draw the Lewis structures for the following compounds.
a) H2O
b) CH4
c) CO2
d) CO32-
e) NH3
f) PCl5
g) SF4
h) ClF2-
h) I3-
i) SF6
j) IF5
k) TeCl4-
CHEM 3.4 Questions
11
Draw the Lewis structures and work out the shapes for the following
a) N2O
b) NO2
c) NO3-
d) NO2-
e) OCl2
f) SeF2
g) PH3
h) POCl3
h) XeO4
i) SO32-
j) XeO3
k) XeOF4
CHEM 3.4 Questions
l) XeOF2
m) CO
n) TeF5-
o) IF4+
p) SF5+
q) IF6+
12
Draw the following molecules with arrows to represent polar bonds (electronegativity
difference >0.5) to work out is they are polar or non polar.
a) H2O
b) NH3
c) CH4
d) CH3Cl
e)CH2Cl2
f) SF6
g) CO2
h) N2
CHEM 3.4 Questions
1. Write the s, p, d electron configuration for P3-.
2. Write the s, p, d electron configuration for Ge.
3. Write the s, p, d electron configuration for Cr and Cu.
4. Write the s, p, d electron configuration for Fe3+.
5. What is the atomic radius?
6. Why does Cl have a smaller radius than S?
7. Why is the atomic radius of K larger than Na?
8. Why is the atomic radius of Na+ smaller than Na?
9. Why is the atomic radius of Cl- larger than that for Cl?
10. Draw an equation to show the first ionisation of Cl.
11. Why does it take energy to remove an electron from an atom?
12. Why is the ionisation energy of Mg larger than Na?
13. Why is the ionisation energy of N higher than that of O?
14. Why is the ionisation energy of S less the O?
15. Define electronegativity.
16. Explain fully why F is the most electronegative element.
17. Complete the following table.
18. What do I mean if I say that AlCl3 is 60% ionic?
19. Explain why instantaneous dipoles occur.
20. What causes a permanent dipole in a molecule?
CHEM 3.4 Questions
21. What is needed for hydrogen bonding to occur?
22. Will CH4 or CCl4 have the lowest melting point? Why?
23. Why does HCl have a lower melting point than HBr?
24. Which is more important when comparing the strength of inter molecular attractions,
instantaneous or permanent dipoles?
25. How many valence electrons each of CO32-, CH3Cl and SF6 Have?
26. Draw the Lewis structures for CO32-, CH3Cl and SF6.
27. What are the shapes of CO32-, CH3Cl and SF6?
28. Are CO32-, CH3Cl and SF6 polar or non-polar?
29. What are the labeled angles on the following molecule?
Why is the angle between bonds in water 105 and not 109 as you might expect?
Glossary
Electron configuration, sub-level, orbital, atomic radius, ionic radius, ionisation
energy, electronegativity, polar, hydrogen bond, instantaneous dipole, intra
molecular, inter molecular, VSEPR, Lewis structure, lone pair, valence,
radioactivity, electron.