Topic 8- Periodicity

Question 1

Atomic radii across Period 3?

Answer 1

-Atomic radii decreases, increased nuclear charge, increased protons as it pulls electrons towards nucleus.

Question 2

Period 3~ melting points (Metallic)
~Na,Mg,Al

Answer 2

• Increasing charge
• Increase delocalised electron
• Decreased radius
• Increased metallic bond

Question 3

Melting point~ Macromolecular
Silicon

Answer 3

• Strong covalent bond, lots of energy needed to overcome
  Highest MP.

Question 4

Simple Molecular- Phosphorous

Answer 4

Lower than Silicon due to it being a simple molecular structure. MP determined by the weaker van der waal bonds.

Question 5

Simple molecular- S8

Answer 5

S8 has a higher MP than P4 due to larger simple molecular structure, more van der waals therefore higher MP.

Question 6

Simple Molecular- CL2

Answer 6

Lower melting point than P and S due to smaller simple molecular structure, lower van der waals therefore lower MP.

Question 7

Individual atom- Ar

Answer 7

Lowest MP
Lowest van der waal therefore lower MP.

Question 8

What is ionisation?

Answer 8

The minimum energy required to remove 1 mole of electron from one mole of atoms in a gaseous atom.
Na(g)-> e^-+ Na^+(g)

Question 9

What is shielding?

Answer 9

Higher electron shells between the positive nucleus and electron being removed,less energy, weaker attraction.

Question 10

What is the atomic size?

Answer 10

Larger atoms the further outer electrons are from the nucleus therefore attractive force between positive nucleus and outer electron weakens therefore easier to remove an electron.

Question 11

What is the nuclear charge

Answer 11

The more protons in the nucleus, the higher attraction between the nucleus and the outer shell, therefore more energy needed to remove the outer electron.

Question 12

What are the 1st ionisation energy trends in Groups??

Answer 12

DECREASE!
Atomic Radius
Increases going down the group.
Outer electron further from nucleus therefore a weaker attractive force needed to remove electron decreases.
Shielding
Increases going down the group, shells between the nucleus and outer electron increases therefore weaker attraction force therefore less energy needed to remove electron.

Question 13

What are the 1st ionisation energy trends across a period?

Answer 13

INCREASES
More protons, higher nuclear attraction
Increases energy needed too remove outer electrons.