Sec 3 Chemical Bonding

Which statement about the formation of magnesium chloride is correct?

• A magnesium atom gains 2 electrons to form a magnesium ion.

• A magnesium atom loses 2 electrons to form a magnesium ion.

• A chlorine atom gains 2 electrons to form a chloride ion.

• A chlorine atom loses 1 electron to form a chloride ion.

The atoms of element Y have the electronic configuration 2,8,6. Which statement about element Y is correct?

• It forms an ionic compound with sodium.

• It forms an ion with charge 2+.

• It has 6 protons in the outer shell of the atom.

• It only reacts with non-metals.

2 elements Z and Y react to form a compound. What is the chemical formula of the compound?

• ZY

• Z₂Y

• ZY₂

• Z₂Y₂

The dot-and-cross diagram shows the arrangement of the outer shell electrons for a compound XY₃. What could X and Y be?

• X: sulfur, Y: chlorine

• X: phosphorus, Y: chlorine

• X: nitrogen, Y: oxygen

• X: carbon, oxygen

How many electrons are shared in the covalent bonding of ammonia, NH₃?

• 2

• 4

• 6

• 8

Which compound has both ionic and covalent bonds?

• ammonium chloride

• carbon dioxide

• sodium chloride

• iron(III) oxide

Which substance is likely to be sodium chloride?

• A

• B

• C

• D

Gold has the chemical symbol, Au. What is the chemical formula of gold(III) sulfate?

• AuSO₄

• Au₂SO₄

• Au₂(SO₄)₃

• (Au)₂(SO₄)₃

Phosphorus and arsenic are both in group 15 of the Periodic Table. The chemical formula of sodium phosphate is Na₃PO₄. What is the chemical formula of magnesium arsenate?

• MgAsO₄

• Mg₃AsO₄

• Mg₃(AsO₄)₂

• Mg₂(AsO₄)₃

Brass is an alloy of copper and zinc. Which statement is correct?

• It melts at a fixed temperature.

• It has properties of copper and zinc.

• It has a fixed ratio of copper to zinc.

• It decomposes into copper and zinc in a chemical reaction.