sc7, types of substances (paper 1 and 2)

Question 1

describe the physical properties of simple molecular covalent

Answer 1

low melting and boiling points (weak intermolecular forces)

Question 2

describe the physical properties of giant covalent molecular

Answer 2

high melting and boiling points

Question 3

describe the physical properties of metallic

Answer 3

high melting anf boiling points

Question 4

describe the solubility of simple molecular covalent

Answer 4

a few are soluble in water

Question 5

describe the solubility of giant covalent molecular

Answer 5

insoluble in water

Question 6

describe the solubility of metallic

Answer 6

insoluble in water

Question 7

describe the conductivity of simple molecular covalent

Answer 7

most don’t conduct heat and electricity

Question 8

describe the conductivity of giant covalent molecular

Answer 8

most don’t conduct heat and electricity

Question 9

describe the conductivity of metallic

Answer 9

conduct in solid and liquid

Question 10

describe where simple molecular covalent structures can be found

Answer 10

most non-metal elements and compounds

Question 11

describe where giant covalent molecular structures can be found

Answer 11

a few non-metal elements and compounds

Question 12

describe where metallic structures can be found

Answer 12

in all metals

Question 13

describe the structure of simple molecular covalent

Answer 13

molecules consisting of a few atoms

Question 14

describe the structure of giant covalent molecular

Answer 14

billions of atoms held together in a lattice structure in covalent bonds

Question 15

describe the structure of metallic

Answer 15

• billions of ion held together with electrostatic forces
• in a giant lattice structure of positive ions in a sea of delocalized electrons

Question 16

explain why metallic structures are malleable/ductile

Answer 16

layers of positive ions / atoms can slide over each other

Question 17

define allotrope

Answer 17

different structurak forms of the same element in the same physical state

Question 18

what are the two main examples of allotropes of carbon

Answer 18

diamond and graphite

Question 19

what types of structures are diamond and graphite

Answer 19

giant covalent structure

Question 20

properties of diamond

Answer 20

• each atom covalently bonded to four others
• high melting + boiling points
• hard
• sparkly in light
• doesn’t conduct

Question 21

properties of graphite

Answer 21

• each weakly atom covalently bonded to three others
• high melting point
• slippery, soft
• can conduct (each element has 1 delocalized electron)

Question 22

define fullerene

Answer 22

when a sheet a graphite (graphene) can be isolated and made into other structures

Question 23

what are the two main examples of fullerenes of graphite

Answer 23

buckyballs (more specifically buckministerfullerene, C60) and nanotubes

Question 23

how can molecules also form polymers

Answer 23

they are made of monomers, repeating units of small, simple molecules joined in a chain

Question 24

properties of buckyballs (buckministerfullerene, C60)

Answer 24

• can conduct
• soft in solid state because of weak intermolecular forces

Question 25

properties of nanotubes

Answer 25

• can conduct
• very strong because of many strong covalent bonds

Question 26

why do some metals dissolve in water

Answer 26

because they react with water to produce soluble metal hydroxides

Question 27

what are the different bonding models

Answer 27

• drawn/structural formula
• dot and cross
• space filling model
• ball and stick model

Question 28

advantages of drawn/structural formula

Answer 28

• shows formula of element/compound
• shows numbers of atoms in each molecule

Question 29

advantages of dot and cross

Answer 29

• shows symbol, bond and formula for each atom
• shows non bonding pairs

Question 30

advantages of space filling model

Answer 30

• more accurate size of atoms relative to the bonds

Question 31

advantages of ball and stick model

Answer 31

• shows how each atom is bonded to others
• shows three dimensional shape

Question 32

disadvantages of drawn/structural formula

Answer 32

• no three dimensional shape
• no bonding and non bonding electrons

Question 33

disadvantages of dot and cross

Answer 33

• inaccurate molecule shape
• no three dimensional shape

Question 34

disadvantages of space filling model

Answer 34

• may not see all atoms

Question 35

disadvantages of ball and stick model

Answer 35

• doesn’t show bonding electrons
• doesn’t show chemical symbol