OCR Chemistry A -- 2.2.2 Bonding, Structure and Periodicity

Which of the below is described by: high melting point, can conduct electricity, soluble in water.

• Al(s)

• carbon (graphite)

• CH₄(g)

• NaCl (aq)

What is the bond angle of a H₃O⁺ ion?

• 104.5°

• 107°

• 109.5°

• 120°

Answer explanation

The H₃O⁺ ion has three bonded pairs and one lone pair.

Which would have the strongest permanent dipoles?

• CO

• ClF

• HF

• HI

Answer explanation

This pair of elements has the biggest difference in electronegativity.

Which would have a permanent dipole?

• H₂O

• CO₂

• CH₄

• NH₄⁺

Answer explanation

H₂O is non-symmetrical, causing a dipole.

Which molecules have the strongest intermolecular forces?

• BF₃

• H₂S

• NH₃

• H₂

Answer explanation

NH₃ has hydrogen bonding, others do not.

TICK ALL TRUE STATEMENTS

• Water has hydrogen bonds which increase the boiling point.

• Water as a solid is more dense than as a liquid

• Water has bond angles of 180^o.

Answer explanation

water is less dense as a solid

water has bond angles of 104.5^o.

Which structure would sulfur(s), S₈, have?

• simple covalent molecules

• simple molecular lattice

• giant covalent lattice

• giant ionic lattice

Answer explanation

"simple covalent molecules" is not a type of lattice. The molecules form a lattice, held together by intermolecular forces of attraction.

Which structure would MgCl₂, have?

• simple covalent molecules

• simple molecular lattice

• giant covalent lattice

• giant ionic lattice

Answer explanation

the is a compound: a non-metal and metal.

They form anions and cations

held together by electrostatic forces (ionic bonding)

Which structure would silica, SiO₂, have?

• giant metallic lattice

• simple molecular lattice

• giant covalent lattice

• giant ionic lattice

Answer explanation

SiO₂ is the other common example of giant covalent

atoms of Si and O

held in a giant lattice by covalent bonds

Which structure would calclium, Ca, have?

• giant metallic lattice

• simple molecular lattice

• giant covalent lattice

• giant ionic lattice

Answer explanation

calcium is a metal

a lattice of metal cations (Ca²⁺)

and delocalised electrons

metallic bonding