Bonding - Application & Understanding

Question 1

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Explain why sodium chloride has a high melting point.

Answer 1

Strong electrostatic forces between Na⁺ and Cl⁻ ions require lots of energy to break.

This high melting point is due to the ionic bonding in the crystal lattice structure.

Question 2

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Explain why oxygen (O₂) has a low boiling point.

Answer 2

It is a simple covalent molecule with weak intermolecular forces.

The weak van der Waals forces between O₂ molecules allow them to be easily separated.

Question 3

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Explain why graphite conducts electricity but diamond doesn’t.

Answer 3

Graphite has delocalised electrons; diamond has no free electrons.

The structure of graphite allows electrons to move freely, while diamond’s rigid structure does not.

Question 4

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Why does magnesium oxide have a higher melting point than sodium chloride?

Answer 4

Mg²⁺ and O²⁻ ions have stronger electrostatic attraction due to higher charges.

The greater charge on magnesium and oxide ions results in a stronger ionic bond.

Question 5

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Why does ice float on water?

Answer 5

Ice has a more open structure due to hydrogen bonding, making it less dense.

This unique structure of ice allows it to be less dense than liquid water.

Question 6

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Why do metals conduct heat well?

Answer 6

Delocalised electrons transfer energy quickly through the structure.

The presence of free-moving electrons in metals facilitates efficient energy transfer.

Question 7

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Why does chlorine exist as Cl₂ molecules?

Answer 7

Each chlorine atom shares one electron to achieve a full outer shell.

This covalent bonding allows chlorine atoms to stabilize by sharing electrons.