Question 1

Which of the following best explains why the melting point of sodium (Na) is lower than that of magnesium (Mg)?

Accepted Answer

Sodium has a larger atomic radius, resulting in weaker metallic bonding due to less effective overlap of atomic orbitals.

Question 2

Which type of structure is most likely to result in the highest melting point for an element?

Accepted Answer

Giant covalent structure

Question 3

Why does the melting point of alkali metals generally decrease as you move down Group 1 in the periodic table?

Accepted Answer

The atomic radius increases, weakening the metallic bond between atoms.

Question 4

Which allotrope of carbon is predicted to have the lowest melting point?

Accepted Answer

Buckminsterfullerene (Fullerene)

Question 5

Which of the following best explains why graphite conducts electricity but diamond does not?

Accepted Answer

Graphite has delocalized electrons that can move freely between layers, while diamond does not.

Question 6

Which element in Period 3 has the highest melting point, and what is the main reason for this?

Accepted Answer

Silicon, due to its giant covalent structure

Question 7

Given the trend in melting points across Period 3, which of the following best describes the change from sodium to aluminum?

Accepted Answer

Melting point increases due to increasing strength of metallic bonding as the number of delocalized electrons increases.

Question 8

Which of the following equations correctly represents the relationship between the strength of metallic bonding and the number of delocalized electrons per atom?

Accepted Answer

$$ F \propto n_{e^-} $$

Question 9

Which of the following best explains why buckminsterfullerene (C$$_{60}) is a $$poor conductor of electricity compared to graphite?

Accepted Answer

Buckminsterfullerene has localized electrons and lacks delocalized electrons for conduction.

Question 10

A student claims that the melting point of magnesium is higher than that of sodium because magnesium atoms are smaller. Is this claim correct? Why or why not?

Accepted Answer

No, the main reason is that magnesium has more delocalized electrons per atom, strengthening the metallic bond.

Question 11

Which of the following best describes the trend in melting points for Group 2 metals from magnesium to calcium?

Accepted Answer

The melting point increases due to a change in the metallic crystal structure.

Question 12

Which of the following statements about the melting points of elements is correct?

Accepted Answer

Elements with giant covalent structures generally have higher melting points than those with simple molecular structures.

Question 13

Which of the following best explains the periodic trend in melting points for Period 3 elements from sodium to argon?

Accepted Answer

Melting point increases from sodium to silicon due to stronger metallic and covalent bonding, then decreases sharply for nonmetals with simple molecular structures.

Question 14

Which of the following is a correct real-world application of the concept of metallic bonding strength?

Accepted Answer

Aluminum is used in aircraft construction because its strong metallic bonds give it high strength and melting point.

Question 15

Which of the following best explains why the melting point of argon is much lower than that of silicon?

Accepted Answer

Argon exists as individual atoms with weak London dispersion forces, while silicon has a giant covalent structure.

Periodic Trends: Melting Point and Structure in the Periodic Table

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