Periodicity

Question 1

Explain the decrease in atomic radii across Period 3 (Na - Cl)

Answer 1

Number of protons increase (proportional with electrons)
Shielding remains the same
So greater nuclear attraction

Question 2

Why does Mg (Group 2) have a higher boiling point than Na(Group 1) despite being in the same period ?

Answer 2

Charge of magnesium ion is stronger (2+ > 1+)
More outer electrons/delocalised electrons
Stronger electrostatic attraction between positively charged metal ion and delocalised electrons.

Question 3

What do you talk about when a question asks you about the differing Ionisation Energies ?

Answer 3

Nuclear Charge (N)
Distance of electron to nucleus (D)
Shielding (S)
Nuclear attraction (A)
Energy required to remove (E)

Question 4

Explain increase in ionisation energies on Period 1

Answer 4

Radii decreases
Increase in number of protons
Shielding remains the same/similar

Question 5

State the definition for ‘ First Ionisation Energy ‘

Answer 5

Energy required
To remove one mole of electrons
From atoms in their gaseous state
To form 1 mole of gaseous ions

Question 6

Where is there a dip in the ionisation energy in period 2 ?

Answer 6

Lithium
Boron
Oxygen

Question 7

Where is there dips in ionisation energy in period 3 ?

Answer 7

Sodium (Na)
Aluminium ( Al)
Sulfur (S)

Question 8

Why are there dips in ionisation energy graphs ?

Answer 8

Either :
Due to different amounts of electrons being lost from orbitals (1 lost from boron in p < 2 lost from s in beryllium)
OR
Due to electron configuration - > more paired electrons = more repulsion
Therefore a lowered ionisation energy