CHEM 001A
Experiment 3
Periodic Table and Periodic Law
Aim: In this experiment we will observe the chemical reactivity of chlorine, bromine and iodine,
the relative acidic or basic strength of the hydroxides or oxides in the third period of the periodic
table, and the relative solubility of the hydroxides of several metals through a series of
qualitative tests.
Procedure: Refer to CHM 151 Lab Manual page 33 to page 36.
Result:
A) Periodic Trends in Physical Properties
1. Figure 1.
a. As the atomic number of the halogen group increases, the ionisation energy
decreases.
b. The ionisation energy decreases when moving down a group.
c. The ionisation energy increases when moving across a period from right to left.
2. Figure 2.
a. Group 1 has the largest atomic radii.
b. The atomic radii increases as you move down a group of elements.
c. As atomic radii increases the ionisation energy decreases.
3. Figure 3.
a. Group 7 has the highest electron affinities.
b. Yes, as shown in the graph in Procedure A, the trend between atomic number
3~10 (period 1) is similar to the trend between atomic number 11~ 18 (period 2).
c. Yes, electron affinities and atomic radii are inversely correlated, as atomic radius
increases, the electron affinities decreases.
4. Figure 4.
a. The melting point increases and decreases across a period, the 2 ends of a
period usually has the lowest melting point, the melting point increases as you
move towards the middle of the period.
b. Carbon has the highest melting point. But its congeners don’t all have high
melting points.
5. Figure 5.
a. Sodium, potassium, rubidium and caesium (group 1) has the highest molar
volume.
b. The molar volume and the atomic radii has similar trends as atomic number
increases.
c. The molar volume and the ionisation energy seems to have an inverse
correlation between them.
6. Figure 6.
a. The density increases then decreases across period 2 and 3.
, b. The density and melting point has a positive correlation, as density increases, the
melting point increases.
B) Ionization Energies for Aluminium
1. There is a significant increase in the 4th ionization energy because we are taking away
the 1s electron which were formerly in the complete closed shell.This is a stable,
complete shell, so extra energy is required to remove an electron from it.
2. There is an even more significant increase in the 12th ionization energy because
by the time we have removed 11 electrons, we are down to an electron
configuration of 1s.This is a stable, complete shell, so extra energy is required to
remove an electron from it.
3. Both magnesium and silicon are under the same period as aluminum.The 11th
ionization energy of magnesium and the 13th ionization energy of silicon have
significant increases because we are removing the 1s electron from the complete
shell, so there are more energy required.
C) The Appearance of Some Representative Elements
Element Physical State (g,s,l) Physical Appearance and Other Observations Color
Na S Soft and bright, quickly becomes dull when Silvery
reacts with oxygen in the air white
Mg S Light in weight, shiny and strong Silvery
grey
Al S Light in weight, shiny and strong Silvery
white
Si S Hard and brittle in crystalline form Blue grey
S8 S Odorless and tasteless powder Yellow
Cl2 g Gas with pungent and sharp smell Yellowish
green
Br2 l Toxic and odor liquid that evaporates easily Reddish
brown
I2 s glittering crystalline Dark
purple
D) The Chemical properties of the Halogens
Reaction Observation Equation for Observed Reaction
Cl2 + Br- Blood red solution Cl2 + 2KBr → 2KCl + Br2
Experiment 3
Periodic Table and Periodic Law
Aim: In this experiment we will observe the chemical reactivity of chlorine, bromine and iodine,
the relative acidic or basic strength of the hydroxides or oxides in the third period of the periodic
table, and the relative solubility of the hydroxides of several metals through a series of
qualitative tests.
Procedure: Refer to CHM 151 Lab Manual page 33 to page 36.
Result:
A) Periodic Trends in Physical Properties
1. Figure 1.
a. As the atomic number of the halogen group increases, the ionisation energy
decreases.
b. The ionisation energy decreases when moving down a group.
c. The ionisation energy increases when moving across a period from right to left.
2. Figure 2.
a. Group 1 has the largest atomic radii.
b. The atomic radii increases as you move down a group of elements.
c. As atomic radii increases the ionisation energy decreases.
3. Figure 3.
a. Group 7 has the highest electron affinities.
b. Yes, as shown in the graph in Procedure A, the trend between atomic number
3~10 (period 1) is similar to the trend between atomic number 11~ 18 (period 2).
c. Yes, electron affinities and atomic radii are inversely correlated, as atomic radius
increases, the electron affinities decreases.
4. Figure 4.
a. The melting point increases and decreases across a period, the 2 ends of a
period usually has the lowest melting point, the melting point increases as you
move towards the middle of the period.
b. Carbon has the highest melting point. But its congeners don’t all have high
melting points.
5. Figure 5.
a. Sodium, potassium, rubidium and caesium (group 1) has the highest molar
volume.
b. The molar volume and the atomic radii has similar trends as atomic number
increases.
c. The molar volume and the ionisation energy seems to have an inverse
correlation between them.
6. Figure 6.
a. The density increases then decreases across period 2 and 3.
, b. The density and melting point has a positive correlation, as density increases, the
melting point increases.
B) Ionization Energies for Aluminium
1. There is a significant increase in the 4th ionization energy because we are taking away
the 1s electron which were formerly in the complete closed shell.This is a stable,
complete shell, so extra energy is required to remove an electron from it.
2. There is an even more significant increase in the 12th ionization energy because
by the time we have removed 11 electrons, we are down to an electron
configuration of 1s.This is a stable, complete shell, so extra energy is required to
remove an electron from it.
3. Both magnesium and silicon are under the same period as aluminum.The 11th
ionization energy of magnesium and the 13th ionization energy of silicon have
significant increases because we are removing the 1s electron from the complete
shell, so there are more energy required.
C) The Appearance of Some Representative Elements
Element Physical State (g,s,l) Physical Appearance and Other Observations Color
Na S Soft and bright, quickly becomes dull when Silvery
reacts with oxygen in the air white
Mg S Light in weight, shiny and strong Silvery
grey
Al S Light in weight, shiny and strong Silvery
white
Si S Hard and brittle in crystalline form Blue grey
S8 S Odorless and tasteless powder Yellow
Cl2 g Gas with pungent and sharp smell Yellowish
green
Br2 l Toxic and odor liquid that evaporates easily Reddish
brown
I2 s glittering crystalline Dark
purple
D) The Chemical properties of the Halogens
Reaction Observation Equation for Observed Reaction
Cl2 + Br- Blood red solution Cl2 + 2KBr → 2KCl + Br2
