Chemistry mock p1 Flashcards
What is periodicity?
Periodicity is the trends of elements across a period
Does atomic radius increase or decrease across a period and why?
Atomic radius decreases across a period because the proton number increases, so the positive charge of the nucleus increases. Electrons are pulled closer to the nucleus, making the atomic radius smaller. Extra electrons are added to outer energy level so add no shielding effect.
Does ionisation energy increase or decrease across a period and why?
Ionisation energies increase across a period because the proton number increases so there is a stronger nuclear attraction. Extra electrons add no shielding effect.
Why is there a drop in ionisation energy between group 2 and 3?
Due to 3p orbital being at a higher energy level than 3s, so is further away from the nucleus. The 3p orbital has shielding from 3s orbital. Overrides effect of increasing nuclear charge
Why is there a drop between group 5 and 6?
Electron repulsion
Easier to remove an electron from a partially filled p orbital than a singly filled orbital due to electron repulsion.
How do metal ions make carbonates and nitrates unstable?
The presence of metal cations polarises the anion electron cloud, making it less stable
Does thermal stability of carbonates and nitrates increase or decrease down a group and why?
Increases, as larger cations cause less distortion than small cations as they have a lower charge density. Down a group, the cations get larger making carbonates/ nitrates more thermally stable.
Are group 1 or 2 carbonates/nitrates more stable and why?
Group 1 compounds are more thermally stable as group 2 has a higher charge, and therefore a higher charge density, meaning there is more distortion of the anion and it is less stable.
Do group 1 carbonates decompose when heated?
They are stable when heated with a Bunsen burner and therefore do not decompose.
Apart from Li2c03 which decomposes to Li20 and C02
What do group 1 nitrates decompose into when heated?
Group 1 nitrates decompose to form the nitrite and oxygen.
2MNO3 (s) –> 2MN02 (S) + 02(g)
Apart from Li2CO3 that decomposes into Li2O, NO2 + 02
What do group 2 carbonates decompose to form when heated?
They decompose to form oxide and carbon dioxide
MCO3 (s)–> MO(s) + CO2 (g)
What do group 2 nitrates decompose to form when heated?
Oxide, Nitrogen dioxide and oxygen
2M(NO3)2 (s) –> 2MO(s) + 4NO2 (g) + O2 (g)
How is the thermal stability of nitrates tested?
Time taken to produce a certain amount of oxygen
(enough to relight a glowing splint)
Time taken for an amount of NO2 to be produced
(toxic so needs to be done in a fume cupboard)
How is the thermal stability of carbonates tested?
Time taken to produce a certain amount of CO2
Test for CO2 using lime water- turns it cloudy
What flame colour does Lithium produce?
Red
What flame colour does sodium produce?
Orange/ Yellow
What flame colour does potassium produce?
Lilac
What flame colour does rubidium produce?
Red
What flame colour does caesium produce?
Blue
What flame colour does calcium produce?
Brick-red