Module 3

Question 1

mendeleev

Answer 1

arranged in order of atomic mass
grouped elements with similar properties
left gaps for undiscovered elements
- predicted properties of missing elements

Question 2

modern periodic table

Answer 2

positions linked to physical and chemical properties
increasing atomic number (L to R)
grouped atoms with same number of electrons in outer shell
periods- number of the highest energy electron shell

Question 3

first ionisation energy

Answer 3

energy required to remove one electron from each atom in one mole of gaseous atoms of an element to form one mole of gaseous 1+ ions

Question 4

factors affecting ionisation energy

Answer 4

atomic radius
nuclear charge
electron shielding

Question 5

second ionisation energy

Answer 5

energy required to remove one electron from each ion in one mole of gaseous 1+ ions of an element to form one mole of gaseous 2+ ions

Question 6

predictions from successive ionisation energy

Answer 6

no of electrons in outer shell
group of element in periodic table
identity of an element

Question 7

metallic bonding

Answer 7

strong electrostatic attraction between cations and delocalised electrons
cations- fixed maintaining shape
DE- mobile and able to move throughout structure
giant metallic lattice

Question 8

properties of metals

Answer 8

strong metallic bonds
high elec condictivity
high mp/bp
not soluble

Question 9

giant covalent

Answer 9

billions of atoms held together by strong covalent bonds to form giant covalent lattice

Question 10

giant covalent properties

Answer 10

high mp/bp
insoluble
non conductors (except graphene and graphite)

Question 11

graphene

Answer 11

single layer of graphite
hexagonally arranged carbons
linked by strong covalent bonds

Question 12

graphite

Answer 12

parallel layers of hexagonally arranged carbon atoms
layers boded by weak london forces
spare electron from each carbon atoms becomes delocalised

Question 13

group 2 trends

Answer 13

ionisation energies decrease down group
reactivity increase down group

Question 14

halogens

Answer 14

reactivity decreases down group
boiling point increase down group

Question 15

halogen- halide displacement

Answer 15

colour change

Question 16

water-> cyclohexane halogen solutions

Answer 16

I- brown-> violet
Br- orange-> paler orange
Cl- pale green-> slightly darker green

Question 17

disproportionation

Answer 17

redox reaction
same element both oxidised and reduced

Question 18

chlorine + water

Answer 18

for each chlorine molecule, one atom is oxidised, other is reduced
produces HClO and HCl

Question 19

chlorine + cold, dilute aqueous NaOH

Answer 19

Cl2 + 2NaOH -> NaClO (aq) + NaCl (aq) + H2O

Question 20

pros/cons of chlorine use

Answer 20

kills bacteria in water so it is safe to drink
respiratory irritant in small concentrations
large conc can be fatal

Question 21

tests for halides

Answer 21

aqueous halide ions react with aqueous silver ions to form silver halide precipitate

Question 22

halide test gen eq

Answer 22

Ag+ (aq) + X- (aq) –> AgX (s)

Question 23

qualitative analysis

Answer 23

relies on observations not measurements
eg, gas bubbles, precipitates, colour changes, identification of gases

Question 24

carbonate test

Answer 24

react with acids to form CO2
add dilute nitric acid to solid/ solution, see if theres gas produced, bubble gas through limewater

Question 25

sulfate test

Answer 25

BaSO4 is insoluble
aqueous barium ions added to solution of unknown compound

Question 26

sequence of tests

Answer 26

carbonate
sulfate
halide

Question 27

test for ammonium ion

Answer 27

add NaOH (aq) to solution of ammonium ion
ammonia gas produced
mixture warmed, gas released
test with moist pH indicator paper
paper turns blue is ammonia is present