3.2.1 PERIODICITY

Question 1

What are the 4 blocks in the periodic table?

Answer 1

s, p, d, and f block

Question 2

The periodic table is arranged by increasing A____ N____

Answer 2

Atomic Number

Question 3

Why might an element be in one of these 4 blocks?

Answer 3

Because its highest energy electron (s) is in this block.

Question 4

What is the trend in melting/boiling points across period 3?

Answer 4

Mpts and Bpts increase from Na-Si. They decrease from P-Ar.

Question 5

Why does the melting/boiling point increase from Na-Si?

Answer 5

Na, Mg, and AL have metallic bonding. These get stronger as there is an increase in delocalised electrons and there is a higher charge, so there is a stronger electrostatic attraction.
Si is a macromolecular crystal that has very strong covalent bonds which require a lot of energy to break all bonds.

Question 6

Why does the melting and boiling point decrease from P-Ar?

What is the order?

Answer 6

There is a general decrease because they are molecular structures that have weak VdW forces.
S8>P4>Cl2

Question 7

Why does Argon have the lowest boiling point?

Answer 7

It is a monatomic molecule that has a full outer shell so very weak VdW forces so lower bpts.

Question 8

State the trend in atomic radius across Period 3?

Answer 8

Decreases.

Question 9

Why does the atomic radius decrease across the period? (4 points)

Answer 9

There is a higher nuclear charge
Across similar shielding
So electrons are pulled more
As there are stronger electrostatic forces of attraction.

Question 10

What is first ionisation energy?

Answer 10

The enthalpy required to remove one electron from one mole of a gaseous atom.

Question 11

What is the formula for 1st ionisation energy?

Answer 11

E (g) –> E+ + e- (Where E is the element)

Question 12

What is the formula for the 2nd ionisation energy?

Answer 12

E+ (g) –> E2+ + e- (Where E is the element)

Question 13

What is the general trend in 1st ionisation energy across Period 3?

Answer 13

increases.

Question 14

Why does 1st ionisation energy generally increase?

Answer 14

Higher nuclear charge so strong electrostatic forces of attraction between the positive nucleus and negative electrons.

Question 15

Why does it deviate between Mg and Al?

Answer 15

1stIE becomes lower.

Al is in a higher subshell (3p>3s) which is slightly away from the nucleus so weaker forces of attraction

Question 16

Why does it deviate between P and S?

Answer 16

1stIE becomes slightly lower

Oxygen has a paired electron in its 3p orbital where there is repulsion so easier to remove the electron.

Question 17

What is periodicity?

Answer 17

a regularly repeating pattern of atomic, physical and chemical properties with increasing atomic numbers.

Question 18

What is a group?

Answer 18

Horizontal columns where elements of that group will have the same number of electrons in their outermost shell.

Question 19

What is a period?

Answer 19

Vertical rows where elements will have the same number of electron shells/similar shielding.