inorganic

Question 1

what happens to the atomic radius across a period

Answer 1

it decreases

1. as the number of protons increases, the positive charge of the nucleus increases.
   electrons are pulled closer to the nucleus
2. the extra electrons that the elements gain across a period are added to the outer energy level do they don’t provide extra shielding effect

Question 2

explain the melting points of

Na, mg, Al, Si, P, S, Cl, Ar

Answer 2

it increases from Na to Al because they are metals so they have strong metallic bonds.

then silicon sky rockets as it’s a macromolecular which has strong covalent bonds

then it goes down as P-Ar as they’re just molecular substances and the MP depend on the strength of the VDW forces

S is higher than C cuz it can be S8 and Ar is the lowest as it can only exist as an individual atom

Question 3

explain what happens to the ionisation energy across the period

Answer 3

it increases

as the nuclear attraction between the outer shell and nucleus due to the number of protons increases

Question 4

what happens to atomic radius down the group

Answer 4

it increases as there’s extra shielding added as you go down

Question 5

what happens to ionisation energy down the group

Answer 5

it decreases down the group

• as the shielding increases decreases the nuclear attraction as the outer electrons are further from the nucleus causing a lower ionisation energy

Question 6

what happens to reactivity down the group

Answer 6

it increases

as the first ionisation decreases it is easier for it to lose electrons, making them more reactive

Question 7

what happens to MP when u go down the group

Answer 7

they decrease

as the ions get bigger the delocalised electrons are further from the positive nucleus so less attraction

so less energy to break bonds

Question 8

explain the solubility trends in Group 2 when it is reacted with a single negative charged ion (ex. OH-)

Answer 8

magnesium —> least soluble

Barium —> most soluble

Question 9

explain the solubility trends in Group 2 when it is reacted with a double negative charged ion (ex. SO4 2-)

Answer 9

magnesium —> most soluble
barium —> least soluble

Question 10

what’s the test for sulphate ions

Answer 10

add acidified barium chloride and dilute HCI to a solution with sulphate ions then a
WHITE PPT of barium sulphate will form

Question 11

why are group 2 compounds called alkaline earth metals

Answer 11

because they are used to neutralise acids

1. CaOH2 is used for agriculture to neutralise acid soils
2. MgOH2 is used in digestion tablets to neutralise stomach acid

Question 12

what’s ionic equation for neutralisation

Answer 12

H+ (aq) + OH- (aq) —> H2O(l)

Question 13

what is barium sulphate used for

Answer 13

it’s used in barium meals

because barium sulphate is opaque in X-rays so this is used to help diagnose problems with stomach or intestines

the barium sulphate coats the tissues making them show up on the X-rays

Question 14

how is magnesium used in extraction of titanium

Answer 14

titanium oxide is converted to titanium chloride by heating it with carbon in a stream of chlorine gas

the titanium chloride is then purified by fractional distillation before being reduced by magnesium in a furnace at 1000 degrees

Question 15

what’s the equation for extraction of titanium

Answer 15

TiCl4(g) + 2Mg(l) —> Ti(s) + 2MgCl2(l)

Mg is reducing agent

Question 16

how does calcium oxide and calcium carbonate remove sulfur dioxide

Answer 16

• powdered calcium oxide and calcium carbonate are mixed with water to make a slurry which is sprayed at the flue gases. the SO2 reacts with the alkaline slurry and produces solid waste — calcium sulphate

Question 17

what’s the formula for removing sulphur dioxide

Answer 17

CaO + 2H2O + SO2 —> CaSO3 + 2H2O

CaCO3 + 2H2O + SO2 —> CaSO3 + 2H2O + CO2

Question 18

explain the halogens physical states and their colours

Answer 18

Fluorine — Gas — Pale Yellow

Chlorine — Gas — Green

Bromine — liquid — Red-Brown

Iodine — Solid — grey

Question 19

explain the BP and electronegativity of the group 7 elements going down the group

Answer 19

BP increases down the group, due to an increase in VDW forces

Electronegativity decreases

the larger the atom the less electron attraction

Question 20

what happens to reactivity in group 7 group going down it

Answer 20

it decreases

because the atoms become larger and outer shell is further from nucleus so electrons are less strongly attracted to it

Question 21

how’s the oxidising of halogens down the group

Answer 21

they’re less oxidising down the group

so if the halide is below the halogen is the reaction then it will displace it

Question 22

how do you know which halogen is present in a solution

Answer 22

CL2
Cl2 + KCl — No reaction
Cl2 + KBr — orange solution (br formed)
Cl2 + KI — brown solution (I formed)

Br2
Br2 + KCl — no reaction
Br2 + KBr — no reaction
Br2 + KI — Brown solution (I2 formed)

I2
I2 + KCl — no reaction
I2 + KBr — no reaction
I2 + KI — no reaction

Question 23

how to make bleach

Answer 23

by mixing chlorine gas with cold, dilute, aqueous NaOH

which makes NaClO

Question 24

what’s formula for bleach

Answer 24

2NaOH (aq) + Cl2(g) —> NaClO(aq) + NaCl(aq) + H2O(l)

Question 25

what happens when you mix water and chlorine

Answer 25

it undergoes disproportionation

Question 26

what does chlorine help with

Answer 26

kills disease causing mucroorganisms some chlorine persists in the water and prevents reinfecting prevents growth of algae eliminating bad smells

Question 27

what are the risks of using chlorine to treat water

Answer 27

chlorine gas is harmful if breathed in chlorine liquid can cause chemical burns chlorine can react with compounds in water and make chlorinated hydrocarbons which cause cancer but the risk is less than untreated water

Question 28

what happens to the reducing power of halides as u go down the group

Answer 28

it increases because bigger ions have weaker attraction so easier to get off

Question 29

test for halides adding silver nitrate solution what will it make

Answer 29

fluoride — no precipitate Chloride — white ppt bromide — cream ppt iodine — yellow ppt

Question 30

adding ammonia solution to test for solublitiy in halides

Answer 30

most soluble Chloride — white ppt — dissolved in DILUTE NH3 bromide — cream ppt — dissolved in CONC NH3 least soluble iodine — yellow ppt — insoluble in conc NH3

Question 31

explain how to test for ions — cations

Answer 31

FLAME TEST dip nichrome wire loop in conc HCl dip the wire loop into unknown compound hold loop in the clear blue part of a bunsen burner flame observe colour change

Question 32

what’s the colours of the metals during the flame test

Answer 32

calcium — brick red strontium — red Barium — pale green potassium — lilac

Question 33

what’s another way to test for cations other than flame test and what ppt does it form

Answer 33

adding dilute NaOH in test tube containing metal solution and see the ppt that forms with excess and with OH- Mg — slight white ppt/ OH- , white precipitate/ excess OH- Ca — slight white ppt/ OH- and excess OH- Sr — slight white ppt/ OH- and excess OH- Ba — no change/ OH- and excess OH-

Question 34

how do you test for ammonium ions

Answer 34

using damp red litmus paper if ammonia is present paper will turn blue add OH- ions to ammonium ions to make ammonia gas or add NaOH in test tube and heat it up so ammonia is given off

Question 35

how to test for anions (Hydroxides)

Answer 35

use pH indicator to test it 1. dip a piece of red litmus paper into solution if hydroxide ions are present the litmus paper will turn blue cuz it’s Alkaline