S2.1 The ionic model

Question 1

cations

Answer 1

formed when metal atoms lose electrons

Question 2

anions

Answer 2

formed when non-metal atoms gain electrons

Question 3

what do ionic bonds involve

Answer 3

the transfer of electrons from a metallic element to a non-metallic element

Question 4

the ionic bond

Answer 4

• formed by strong electrostatic attractions between oppositely charged ions
• cations and anions are oppositely charged and are attracted to each other
• electrostatic attractions are very strong, and require lots of energy to overcome –> high MPs

Question 5

binary ionic compounds

Answer 5

• composed of ions of two different elements
• metal cation and non-metal anion

Question 6

how are binary ionic compounds named

Answer 6

• named with the cation first, followed by the anion
• anion adopts the suffix -ide

Question 7

ammonium

Answer 7

NH4 +

Question 8

hydroxide

Answer 8

OH -

Question 9

nitrate

Answer 9

NO3 -

Question 10

hydrogencarbonate

Answer 10

HCO3 -

Question 11

carbonate

Answer 11

CO3 2-

Question 12

sulfate

Answer 12

SO4 2-

Question 13

phosphate

Answer 13

PO4 3-

Question 14

cyanide

Answer 14

CN-

Question 15

ionic compounds (what do they exist as and what are they represented by)

Answer 15

• exist as 3D lattice structures
• represented by empirical formulas

Question 16

ionic lattice

Answer 16

• evenly distributed, crystalline structure
• arranged in a regular repeating pattern, so positive charges cancel out negative charges, overall electrically neutral
• alternating cations and anions, so there are strong electrostatic forces of attraction between the oppositely charged, evenly distributed ions

Question 17

properties of ionic compounds: strength

Answer 17

• strong
• strong electrostatic forces keep the ions held strongly together

Question 18

properties of ionic compounds: brittle

Answer 18

• brittle
• ionic crystals can split apart

Question 19

properties of ionic compounds: MP and BP

Answer 19

• high MP and BP
• strong electrostatic forces between the ions in the lattice act in all directions and keep them strongly together
• MP and BP increase with charge density of ions, due to greater electrostatic attraction of charges e.g. Mg2+O2-, has a higher MP than Na+Cl-

Question 20

properties of ionic compounds: volatility (vaporisation of a chemical)

Answer 20

• not volatile
• large amounts of energy are needed to overcome the strong electrostatic forces of attraction –> not volatile

Question 21

properties of ionic compounds: water solubility

Answer 21

• soluble in water
• can form ion-dipole bonds

Question 22

properties of ionic compounds: electricity conduction

Answer 22

• only conduct electricity when molten or in solution
• when molten or in solution, the ions are free to move, and so can conduct electricity
• as a solid, ions are in a fixed position and are unable to move around

Question 23

lattice enthalpy

Answer 23

a measure of the strength of the ionic bond in different compounds, influenced by ion radius and charge

Question 24

lattice dissociation enthalpy (ΔH ⦵ latt)

Answer 24

• the standard enthalpy change that occurs on the formation of 1 mole of gaseous ions from the solid lattice
• ΔH always positive as this is an endothermic process
• ΔH ⦵ latt is always endothermic, energy is always required to break any bonds in the lattice