2.5.2: ionic bonding

Question 1

what’s an ionic bond?

Answer 1

the force of attraction between oppositely charged ions

usually formed between metals and non-metals

Question 2

what happens to the metal atoms?

Answer 2

they lose electrons and form cations

e.g. Na+, Ca2+, Al3+, NH4+

Question 3

what happens to non-metal atoms?

Answer 3

they gain electrons to form anions

e.g. Cl-, O2-, NO3-

Question 4

explain conductivity in solid ionic compounds

Answer 4

when in a solid state, ionic compounds don’t conduct electricity because they’re in a fixed position and there’s no mobile charge carriers

Question 5

explain conductivity in molten/aqueous ionic compounds

Answer 5

when in a molten/aqueous state they do conduct electricity because the ions are mobile and able to carry a current

Question 6

do ionic compounds dissolve in water?

Answer 6

mostly yes (because water is polar and can break down the lattice) however solubility depends on the relative strengths of the attraction within the lattice/between the ions and water molecules - the ions in a compound have large charges the ionic attraction may be too strong for water to break down

Question 7

describe the melting/boiling points of ionic compounds

Answer 7

they have high melting/boiling points because theres a strong electrostatic force of attraction between the oppositely charged ions which means large amounts of energy is required to break these bonds

Question 8

what increases the electrostatic force in an ionic compound?

Answer 8

larger charge
smaller ion

e.g. the melting point of CaF2 is greater than CaCl2 because the fluoride ion is smaller that the chlorine ion so theres a greater force of attraction in CaF2

Question 9

what structures do ionic compounds form?

Answer 9

giant ionic lattices because each ion attracts oppositely charged ions in all directions

Question 10

what do we use to show the formation of ionic compounds?

Answer 10

dot and cross diagrams