04 Chemical Bonding

In which line do all the atoms or ions have eight electrons in their outer shell?

• F^-, Na⁺, Mg²⁺

• F^-, He, Mg²⁺

• H⁺, Na⁺, Ne

• Li⁺, He, Ne

How many atoms does one molecule of ethanol, C₂H₅OH, contain?

• 3

• 4

• 7

• 9

The ‘dot-and-cross’ diagram shows a molecule of hydrogen chloride.

In the molecule of hydrogen chloride,

• the hydrogen atom and chlorine atom share a pair of electrons.

• the hydrogen atom and chlorine atom share a pair of protons.

• the hydrogen atom gives the chlorine atom a proton.

• the hydrogen atom gives the chlorine atom an electron.

The electronic structures of atoms P and Q are shown.

P and Q combine to form a covalent molecule.

What is the formula of the molecule?

• PQ

• PQ₂

• PQ₄

• P₄Q

Covalent bonds are formed when electrons are ….1…. .

Most covalent compounds have ….2…. electrical conductivity.

Which words correctly complete gaps 1 and 2?

• 1 : shared

  2 : high

• 1 : shared

  2 : low

• 1 : transferred

  2 : high

• 1 : transferred

  2 : low

The diagram shows the structure of a methane molecule.

What is the total number of electrons used for bonding in this molecule?

• 2

• 4

• 8

• 10

Which statement about ionic compounds is correct?

• They are easily moulded into different shapes.

• They conduct electricity when they are solid.

• They have high melting points.

• They never dissolve in water.

Which row shows the general properties of an ionic compound?

• high melting point

  not soluble in water

  does not conduct electricity in solid state

  conduct electricity in molten state

• high melting point

  soluble in water

  does not conduct electricity in solid state

  conduct electricity in molten state

• low melting point

  not soluble in water

  does not conduct electricity in solid state

  does not conduct electricity in molten state

• low melting point

  soluble in water

  conduct electricity in solid state

  conduct electricity in molten state

A sodium atom has the electronic configuration 2,8,1 and a chlorine atom has the electronic configuration 2,8,7.

What happens when a sodium atom and a chlorine atom react to form an ionic bond?

• Sodium gains one electron to form Na⁺ and chlorine loses one electron to form Cl^-.

• Sodium gains one electron to form Na^- and chlorine loses one electron to form Cl⁺.

• Sodium loses one electron to form Na⁺ and chlorine gains one electron to form Cl^-.

• Sodium loses one electron to form Na^- and chlorine gains one electron to form Cl⁺.

Which row describes the properties of a simple covalent substance?

• high boiling point

  good electrical conductivity

• high boiling point

  poor electrical conductivity

• low boiling point

  good electrical conductivity

• low boiling point

  poor electrical conductivity