chemistry topic test 2

Question 1

list the properties of metal

Answer 1

good conductors of heat and electricity in solid & liquid state

shiny surface

hard

malleable

ductile

insoluble in water

reasonably high MP

very high BP

Question 2

describe metallic bonding

Answer 2

particles arranged as a lattice of positive cations surrounded by a sea of delocalised electrons

delocalised: can move around atoms and through the lattice

Question 3

explain the metallic property of heat/electricity conduction

Answer 3

when heated energy of cations and delocalised electrons increases

this energy is conducted along metals as cations and electrons collide, transferring electricity

when metals conduct electricity, electrons from one end of the metal cause a similar number of e- to be displaced from the other end

in sold: only electrons move
liquid: both cation and e- carry charge

Question 4

explain the metallic property of malleability and ductility

Answer 4

bonding in metals is NON DIRECTIONAL

layers of atoms can slide over each other without destroying metallic bond

Question 5

explain the metallic property of MP & BP

Answer 5

MP and BP indicate strength of intermolecular forces

relatively high MP and BP due to strong attraction between positive cations and mobile electrons

Question 6

explain the metallic property of hardness

Answer 6

strength of bond is related to charge of positive cations in lattice

metals in group 2 are stronger because atoms release 2 valence electrons (instead of 1 in group 1) and form ions with a +2 charge

Question 7

list the ionic properties

Answer 7

non conductors of electricity in solid state

good electrical conductors in molten or liquid state

hard

brittle

relatively high MP

relatively high BP

varying solubilities in water, insoluble in non-polar solvents

Question 8

describe ionic bonding

Answer 8

ionic solid:
positive and negative ion are arranged in an orderly 3D lattice

each positive ion is surrounded by negative ions and vice versa

ions are held in fixed positions by strong ionic bonds

Question 9

Explain the ionic property of conducting heat/electricity

Answer 9

solid: non conductors because ions are held in a fixed lattice, no mobile charged particles
molten: ions are now mobile, both positive and negative ions carry charge
aqueous: ions dissociate and are able to carry charge

Question 10

Explain the ionic property of MP and BP

Answer 10

high MP and BP:

ionic bonding has large electrostatic forces of attraction between holding atoms together in a lattice

large amount of energy is required to overcome strong ionic bonds

Question 11

Explain the ionic property of hardness

Answer 11

strong ionic bonding extends throughout lattice solid

scratching requires overcoming strong ionic bonds

Question 12

Explain the ionic property of brittleness

Answer 12

ionic lattice doesn’t withstand distortion

when lattice is distorted, like charges align and repel, shattering lattice

Question 13

Describe covalent molecular substances

Answer 13

exist only as discrete molecules

non metals only

solid, liquid or gaseous state

intramolecular forces: strong covalent bond hold atoms together within a molecule

intermolecular forces: weak forces of attraction between molecules

Question 14

list the properties of CMS

Answer 14

non conductors of electricity in solid and liquid

some are weak/good conductors in aqueous solutions

malleable

soft

low Mp and BP

mostly insoluble in water, soluble in non-polar compounds

examples: F2, H2O, O2

Question 15

explain the covalent molecular property of electricity conduction

Answer 15

non conductors in aq, s or l:

molecules are uncharged

electrons are held tightly within covalent bonds

**exception: some CMS react with water to form ions, and become conductors in aqueous solutions

Question 16

explain the covalent molecular property of softness

Answer 16

weak intermolecular forces require little effort to overcome: easy to separate molecules

strong covalent bonds aren’t disrupted

Question 17

explain the covalent molecular property of malleability

Answer 17

molecules can easily slide or be pushed

only weak intermolecular forced exist between them, these can easily be reformed

Question 18

explain the covalent molecular property of BP and MP

Answer 18

low BP and MP:

when CMS are heated, little energy is needed to overcome weak intermolecular forces

Question 19

Describe covalent network substances

Answer 19

solid state only

non metals only

carbon with different structures are called allotropes:
diamond and graphite
examples of CNS substances: silicon, silicon dioxide, carbon

Question 20

List the properties of covalent network substances

Answer 20

non conductors of heat and electricity in solid and liquid state **exception: graphite

extremely brittle

extremely hard

high MP and BP

insoluble in water and most other solvents

reasonably chemically inert

Question 21

Describe the bonding of covalent network substances

Answer 21

arranges in an infinite lattice structure

Question 22

explain the CNS property of electricity/heat conduction

Answer 22

non conductors: no mobile electrons because all valence electrons are tied up in covalent bonds **exception: graphite

Question 23

explain the CNS property of brittleness

Answer 23

if some bonds are broken, the rest of the lattice is placed under stress and shatters

Question 24

explain the CNS property of hardness

Answer 24

extremely hard:

breaking strong covalent bonds requires a very large amount of energy

Question 25

explain the CNS property of MP and BP

Answer 25

high MP and BP: each atom is held in place by strong covalent bonds breaking these bonds requires a very large amount of energy

Question 26

explain the CNS property of solubility

Answer 26

insoluble in water & most other solvents: vary large amount of energy is required to re-arrange existing bonds in any dissolving process

Question 27

explain the CNS property of chemical inertness

Answer 27

reasonably chemically inert: all bonding requirement are fulfilled very large amounts of energy required to re-arrange existing bonds

Question 28

Briefly describe the structure and property of diamond

Answer 28

structure: each carbon atoms is attached to 4 other atoms in a 3D arrangement called a tetrahedron ``` properties: high MP (>3550˚C) non conductor of electricity brittle extremely hard ```

Question 29

Briefly describe the structure and property of graphite

Answer 29

structure: each carbon atoms is covalently bonded to 3 other atoms to form flat 2D sheets called graphene one valence electrons from each carbon remain delocalised properties: high MP good conductor of electricity soft

Question 30

what does the mole represent in mole/mass calculations

Answer 30

measure of the number of particles in a substance 1 mole of any substance contains 6.022 x 10(23) particles

Question 31

what does molar mass represent in mole/mass calculations

Answer 31

equal to atomic, molecule and formula masses in grams

Question 32

What is mass spectrometry used for

Answer 32

determines mass and relative abundance of each isotope present in a sample of an element

Question 33

describe the process of mass spectrometry

Answer 33

``` involved 4 steps: vaporisation ionisation acceleration detection ``` 1. sample is vaporised 2. electrons are fired at the sample and are used to knock off electrons from the atoms, forming ions 3. ions are accelerated and are deflected through a magnetic field (heavier ions are deflected less than lighter ions) 4. Ions are detected and produces a mass spectrum

Question 34

list the separation techniques

Answer 34

sieving filtration evaporation gravity separation distillation fractional distillation

Question 35

Briefly describe the separation technique of filtration

Answer 35

liquid passes through filter paper (filtrate) ad solid residue is left behind used for: separating very fine solid particles from liquids and gases

Question 36

Briefly describe the separation technique of sieving

Answer 36

mixture is passed through a sieve, a series of sieves may be used based on different sizes of components, smaller particles will pass through the hole, larger particles will get caught used for: separating solids from liquids e.g. straining pasta

Question 37

Briefly describe the separation technique of gravity separation

Answer 37

2 tubes containing different mixtures are spun around at a very high speed, forcing part of the mixture to settle at the bottom of the tube used for: separating particles from liquids e.g. separating fat from milk

Question 38

what are the classifications of matter

Answer 38

pure substances: contain 1 type of particle - elements: contain 1 type of atom e.g. Ca, O2 - compounds: contain 2 or more different types of atoms e. g. H2O, NaCl mixtures: contain 2 or more different types of particles - homogenous * uniform composition * e.g. air, soft drinks - heterogenous * non uniform composition * e.g. dirty water, paints