Periodic table

Question 1

what do elements in the same group have ?

Answer 1

same no. of electrons in outer shell — similar chemical properties

Question 2

define first ionisation energy

Answer 2

energy needed to remove 1 mole of electrons from 1 mole of gaseous atoms

Question 3

what type of reaction is ionisation energy reactions ?

Answer 3

endothermic - energy needed to ionise an atom

Question 4

what are the 3 factors of ionisation energy ?

Answer 4

• nuclear charge
• atomic radius
• shielding (greatest factor)

Question 5

what causes high ionisation energy ?

Answer 5

strong attraction between electron and nucleus, so more energy is needed to overcome the attraction and remove the electron

Question 6

ionisation energy … down a group

Answer 6

decreases

Question 7

why does ionisation energy increase across a period ?

Answer 7

positive charge of nucleus increases (no. of protons increases) which pulls electrons closer, decreasing atomic radius

Question 8

why is there a ionisation energy drop between group 2 and 3 ?

Answer 8

• group 3 elements go in p orbitals, which are found further from nucleus than s orbitals (larger atomic radius)
• s electrons provide some shielding

Question 9

why is there a ionisation energy drop between group 5 and 6 ?

Answer 9

• in group 6, electron being removed from orbital with two electrons
• repulsion between two electrons makes it easier to remove an electron

Question 10

what is an allotrope ?

Answer 10

element that has different forms (in the same state)

Question 11

what is the shape of the molecules in diamond ?

Answer 11

tetrahedral (carbon bonded to 4 other carbons)

Question 12

what does sublime mean ?

Answer 12

change from solid straight to gas (no liquid phase)

Question 13

why is diamond a good thermal conductor ?

Answer 13

vibrations travel easily through the stiff lattice

Question 14

what specific structure does diamond have ?

Answer 14

crystal lattice structure

Question 15

what structure does silicon have similar to ?

Answer 15

diamond

Question 16

what causes graphite to be a good lubricant ?

Answer 16

arranged in layers, with weak H-bonds between them (easily broken), so sheets can slide over each other

Question 17

how can graphite conduct electricity ?

Answer 17

has delocalised electrons which are free to move and can carry charge - electric current can flow

Question 18

why is graphite less dense than diamond ?

Answer 18

layers are quite far apart compared to length of covalent bonds

Question 19

why does graphite have a high melting point ?

Answer 19

strong covalent bonds in hexagonal sheets

Question 20

why is graphene known as the best conductor ?

Answer 20

delocalised electrons / as well as it being 2D, so electrons can move quickly above / below sheet

Question 21

what else do the delocalised electrons in graphene do ?

Answer 21

strengthen covalent bonds between carbon atoms (making it strong)

Question 22

a single layer of graphene is …

Answer 22

transparent and light

Question 23

what structure do metals exist as ?

Answer 23

giant metallic lattice structures

Question 24

what is metallic bonding ?

Answer 24

electrostatic attraction between metal cations and (sea of) delocalised electrons

Question 25

how are metals malleable / ductile ?

Answer 25

no specific bonds holding ions together, so can slide past each other

Question 26

what affects metal melting points ?

Answer 26

- no. of delocalised electrons per atom | - site of metal ion

Question 27

why are metals good thermal conductors ?

Answer 27

delocalised electrons can pass kinetic energy to each other

Question 28

what is group 2 known as ?

Answer 28

alkali earth metals

Question 29

group 2 metal + water =

Answer 29

metal hydroxide + hydrogen

Question 30

group 2 metal burnt in (+) oxygen =

Answer 30

solid white metal oxide

Question 31

group 2 metal + water =

Answer 31

dissolved metal hydroxide (OH- ions make really alkaline)

Question 32

what is the use for calcium hydroxide ?

Answer 32

agriculture to neutralise acidic soil

Question 33

what is the use for magnesium hydroxide / calcium carbonate ?

Answer 33

indigestion tablets as antacids

Question 34

give state and colour of fluorine

Answer 34

pale yellow gas

Question 35

give state and colour of chlorine

Answer 35

green gas

Question 36

give state and colour of bromine

Answer 36

red-brown liquid

Question 37

give state and colour of iodine

Answer 37

grey solid

Question 38

what is another way of saying that halogens get less reactive down the group ?

Answer 38

they become less oxidising

Question 39

what is the test for halides ?

Answer 39

- add dilute nitric acid (remove ions) - add silver nitrate solution - silver halide precipitate formed

Question 40

in the halide test, what colour precipitate does chlorine give ?

Answer 40

white

Question 41

in the halide test, what colour precipitate does bromine give ?

Answer 41

cream

Question 42

in the halide test, what colour precipitate does iodine give ?

Answer 42

yellow

Question 43

for Cl, Br, I, describe with ammonia solution

Answer 43

Cl - dissolve in dilute Br - dissolves in conc I - insoluble in conc

Question 44

what is a disproportionate reaction ?

Answer 44

reaction where a molecule is both oxidised and reduced

Question 45

what type of reaction do halogens undergo with alkalis ?

Answer 45

disproportionate reaction

Question 46

what do you get if you react chlorine with sodium hydroxide ?

Answer 46

bleach (NaClO) (disproportionation)

Question 47

give the uses of bleach

Answer 47

water treatment / paper and textiles

Question 48

how is bacteria killed in water ?

Answer 48

- chlorine mixed with water - HCl + chloric(I) acid as products - chloric acid ionises, making chlorate ions - chlorate ions kill bacteria

Question 49

what (two) types of reaction is chlorine + water ?

Answer 49

disproportionation and reversible

Question 50

what is the test for carbonates ?

Answer 50

- add dilute HCl - carbon dioxide will be released - test for CO2 using limewater (turn cloudy)

Question 51

what is the test for sulfates ?

Answer 51

- add dilute HCl - add barium chloride solution - white precipitate of barium sulfate

Question 52

what is test for ammonia gas ?

Answer 52

damp piece of red litmus paper will turn blue

Question 53

what is test for ammonium ions ?

Answer 53

- add NaOH - warm mixture - ammonia gas will be given off

Question 54

state colour of chlorine: RTP - (aq) - dissolved in hexane -

Answer 54

RTP - green (aq) - colourless dissolved in hexane - colourless

Question 55

state colour of bromine: RTP - (aq) - dissolved in hexane -

Answer 55

RTP - brown (aq) - orange dissolved in hexane - orange

Question 56

state colour of iodine: RTP - (aq) - dissolved in hexane -

Answer 56

RTP - grey/black (aq) - brown dissolved in hexane - purple