3.1.3 types of bonding

Question 1

what is ionic bonding

Answer 1

when e- are transferred between atoms
between metal and non-metal
atom will lose or gain e-
form +ive and -ive ions

Question 2

describe the structure of ionic compounds

Answer 2

+ive and -ive ions held together by electrostatic attraction between oppositely charged particles
held in a giant lattice

Question 3

explain the electrical conductivity ionic compounds

Answer 3

can only conduct when molten or aqueous; when solid = ions not free to move + carry charge
when liquid the ions are free to move

Question 4

explain the melting points of ionic compounds

Answer 4

have high m.p due to strong electrostatic forces holding them together; require high E to break

Question 5

explain the solubility of ionic compounds

Answer 5

soluble in water
as H2O mols are polar they pull ions away from compound; attraction
allows them to dissolve
BUT some lattices are too strong to dissolve

Question 6

explain the strength of ionic compounds

Answer 6

are very brittle
when layers are dislocated like charges are close together
causes repulsion
strong enough to split crystal

Question 7

explain what is meant by ‘molecular ion’

Answer 7

some covalently bonded molecules have ionic properties
have a charge
includes OH, CO3, HCO3, NO3, PO4

Question 8

why are +ive ions generally smaller than parent atoms

Answer 8

ratio of protons to electrons are different
+ive ion = more protons
= stronger attraction of e- to nucleus
= e- pulled closer so reduced atomic radius of ion

Question 9

what is covalent bonding

Answer 9

when atoms are bonded together by sharing pairs of electrons
can have single, double, triple bonds

Question 10

describe what simple covalent structures are

Answer 10

atoms are held together by STRONG covalent bonds
molecules in compound held together by weak intermolecular forcesex

Question 11

explain the properties of simple covalent structures

Answer 11

can’t conduct electricity = no delocalised electrons/ions
soluble = mostly organic solvents; can be hydrolysed
low boiling points = weak VDW between mols; easy to break

Question 12

describe what giant covalent structures are

Answer 12

crystal structures w/ large network of covalently bonded atoms
carbon based; can form up to 4 bonds

Question 13

describe the structure of graphite

Answer 13

each C has 3 covalent bonds
1 delocalised e-
arranged in sheets of flat hexagons; sheets held together by weak VDW

Question 14

explain the properties of graphite

Answer 14

slippery = layers can slide; lubricant
conducts electricity = delocalised e-
low density = layers relatively far apart
high m.p = strong covalent bonds
insoluble = strong bonds hard to pull apart

Question 15

describe the structure of diamond

Answer 15

each C bonded to 4 other atoms
tetrahedral shape
no delocalised e-
crystal lattice structure

Question 16

explain the properties of diamond

Answer 16

high m.p = strong covalent bonds
very hard = used in drills + saws
good thermal conductor = vibrations travel easily through stiff lattice
cant conduct electricity = no free e-
insoluble = hard to pull bonds apart

Question 17

explain the properties of silicon dioxide/silica

Answer 17

very hard = rigid tetrahedral structure
high m.p = large no of strong covalent bonds
not electrical conductor = no delocalised e-

Question 18

describe coordinate bonding

Answer 18

both e- in shared pair come from 1 species
only 1 atom donates + 1 atom receives

Question 19

how are coordinate bonds formed

Answer 19

donor species will have LONE PAIRS in outer shell
must have LP to form bond
shown by arrow going out of donor atom