Period 3 Melting Points — Multiple Choice Quiz (15 marks)

1. Which factor causes the melting points to rise from Na → Al across Period 3?

A) Increase in ionic radius
B) Increase in charge and number of delocalised electrons
C) Decrease in charge density
D) Fewer metallic bonds

2. Which Period 3 element has the highest melting point?

A) Aluminium
B) Sodium
C) Silicon
D) Sulfur

3. Why does silicon have a much higher melting point than aluminium?

A) It has more delocalised electrons
B) It has a smaller atomic radius
C) It has stronger metallic bonding
D) It forms a giant covalent lattice with strong Si–Si bonds

4. Which Period 3 element has the lowest melting point?

A) Argon
B) Chlorine
C) Phosphorus
D) Sodium

5. What type of structure do Na, Mg and Al have?

A) Simple molecular
B) Giant metallic lattice
C) Giant ionic lattice
D) Giant covalent lattice

6. Which statement best explains why Al’s melting point is only slightly above Mg’s?

A) Aluminium has fewer delocalised electrons
B) Extra electron–electron repulsion offsets stronger attraction
C) Aluminium has a lower charge density
D) Aluminium’s lattice contains fewer ions

7. Why do S₈ molecules have a higher melting point than P₄ molecules?

A) They contain more electrons and stronger van der Waals forces
B) They have ionic bonds
C) They have metallic bonds
D) They are more reactive

8. Which force must be overcome to melt P₄ or S₈?

A) Covalent bonds
B) Ionic bonds
C) Weak van der Waals (London) forces
D) Metallic bonds

9. What type of bonding exists in Si?

A) Metallic
B) Covalent
C) Ionic
D) Van der Waals only

10. Which element’s melting point is closest to 650 ⁰C?

A) Sodium
B) Magnesium
C) Silicon
D) Sulfur

11. Which group of Period 3 elements shows metallic bonding?

A) Si, P, S
B) P, S, Cl
C) Na, Mg, Al
D) Cl, Ar

12. Why does argon have a very low melting point?

A) It is monatomic with strong bonds
B) It forms covalent bonds
C) It is monatomic with only weak London forces
D) It forms a giant covalent lattice

13. Which statement describes the overall trend in melting points across Period 3?

A) Constant throughout
B) Increase Na→Al, peak at Si, then sharp fall to Ar
C) Decrease steadily across
D) Random variation

14. Which factor primarily determines melting point in metallic structures?

A) Charge and number of delocalised electrons
B) Electronegativity
C) Atomic radius only
D) Number of protons

15. Which explanation links structure to melting point correctly?

A) Si — weak forces between molecules
B) Na — strong covalent bonds
C) P₄ — weak van der Waals forces
D) Al — simple molecular