Periodicity

Question 1

What happens to the atomic radius across a period?

Answer 1

• Dec
• No. proton inc, +ve charge of nucleus inc
• e^- pulled closer to nucleus
• Extra e^- gained across period add to outer energy level so similar shielding

Question 2

Describe + explain the trend in MP of period 3 metals (Na, Mg + Al)

Answer 2

• Inc
• Metallic bonding inc bc
• More protons
• Dec atomic radius
• More delocalised e^-
• Stronger attraction btw ions + delocalised e^-

Question 3

Which element has the highest melting point in period 3? Why?

Answer 3

• Silicon
• Macromolecular
• Many strong covelant bonds
• Lots of energy needed to break

Question 4

Why are the MP btw elements P-Ar low in period 3?

Answer 4

• Simple molecular
• Only VDW forces BTM
• Little energy needed to overcome

Question 5

Explain why sulfur has a higher MP than phosphorus

Answer 5

• Sulfur molecule is a bigger molecule
• Stronger VDW BTM
• More energy needed to break forces

Question 6

Why does aragon have a really low MP?

Answer 6

Exists as monoatomic, v weak VDW

Question 7

Molecule of phosphorus

Answer 7

P₄

Question 8

Molecule of sulfur

Answer 8

S₈

Question 9

Draw the trend in MP of period 3 elements

Answer 9