3.7/3.8 Periodicity (Spec)

Question 1

Element arrangement in Periodic Table

Answer 1

Increasing atomic number
Groups (columns) w/ elements w/ same # of outer-shell electrons, in the same orbital. Similar properties
Periods (rows) w/ same # of electron shells

Question 2

Periodicity

Answer 2

Repeating pattern in properties at regular intervals

Question 3

Nth ionisation energy

Answer 3

Energy required to remove 1 mole of electrons from 1 mole of (n-1) charged particles to form 1 mole of n+ charged particles

Question 4

Trend of successive ionisation energies

Answer 4

Increase for an element:
Increasing electrostatic attraction on each electron from nucleus
Decreasing electron shielding & atomic radius - electron shells removed
Large increase in ionisation energy indicates new main energy level

Question 5

Trend down group in first ionisation energy

Answer 5

Decreases overall:
Nuclear charge increases
Increase in electron shielding and atomic radius outweighs

Question 6

Trend across period in first ionisation energy

Answer 6

Increases overall:
Nuclear charge increases
Similar level of electron shielding, decreasing atomic radius increases effective electrostatic attraction of outer electrons by nucleus

Question 7

Metallic bonding

Answer 7

Strong electrostatic attraction between positive metal ions and a sea of delocalised electrons

Question 8

Melting point trend (Period 2&3)

Answer 8

Increases from Group 1-14, there is a sharp decrease between Group 14 & 15, and melting points are comparatively low in Groups 15-18.

Question 9

Reactions of Group 2 metals with oxygen gas

Answer 9

Group 2 metal + oxygen gas -> Group 2 oxide

Question 10

Reactions of Group 2 metals with water

Answer 10

Group 2 metal + water -> Group 2 hydroxide + hydrogen gas

Question 11

Reactions of Group 2 metals with dilute acid

Answer 11

Group 2 metal + dilute acid -> salt + hydrogen

Question 12

Trend in reactivity down group 2

Answer 12

Reactivity increases because ionisation energies decrease because of decreasing attraction of outer electrons by the nucleus, due to increasing electron shielding and increasing atomic radius

Question 13

Use of calcium hydroxide

Answer 13

Lower soil acidity

Question 14

Uses of magnesium hydroxide and calcium carbonate

Answer 14

Regulate stomach acidity - Antacids

Question 15

Trend in boiling point DOWN Group 7

Answer 15

Increasing due to increasing STRENGTH of London forces, requires increasing quantity of energy to overcome, resulting in a higher boiling point

Question 16

Trend in state at RTP DOWN Group 7

Answer 16

Darker and more solid

Question 17

Trend in reactivity DOWN Group 7

Answer 17

Decreasing reactivity, weaker oxidising agents, lower nuclear attraction, more electron shielding due to more inner shells and increasing atomic radius

Question 18

Disproportionation reaction

Answer 18

Redox reaction where two atoms of the same element are separated so that one is reduced and the other is oxidised

Question 19

Carbonate test

Answer 19

Dilute nitric acid
Gas bubbled through limewater (aqueous calcium hydroxide)
Negative test - Clear solution
Positive test - Cloudy solution as insoluble calcium carbonate forms
K2CO3 + 2HNO3 -> 2KNO3 + CO2 + H2O
Ca(OH)2 + CO2 -> CaCO3(s) + H2O

Question 20

Sulfate test

Answer 20

Aqueous barium nitrate
Positive test - White precipitate of barium sulfate
Negative test - Clear solution

Question 21

Halide test

Answer 21

Aqueous silver nitrate
Positive test: White precipitate of silver chloride
Cream precipitate of silver bromide
Yellow precipitate of silver iodide
Add aqueous ammonia:
Dilute: Silver chloride dissolves
Concentrated: Silver bromide dissolves
Concentrated: Silver iodide does not dissolve

Question 22

Ammonium test

Answer 22

Aqueous NaOH
Heat
Moist litmus
Positive test - Blue
Negative test - Red