The periodic table

Question 1

Periodicity

Answer 1

a regular periodic variation of properties of elements with atomic number and position in the periodic table

Question 2

First ionisation energy-

Answer 2

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

Question 3

Factors affecting ionisation energy

Answer 3

-atomic radius- larger atomic radius, the lower nuclear attraction, therefore lower ionisation energy
-nuclear charge- higher nuclear charge, larger nuclear attraction
-electron shielding- the more shells, the larger the shielding, so less nuclear attraction

Question 4

1st, 2nd and 3rd ionisation energy equations for Li

Answer 4

Li-> e- + Li+
Li+ -> e- + Li2+
Li2+-> e- + Li3+

Question 5

Successive ionisation energies

Answer 5

-electrons removed, less repulsion between remaining electrons, so drawn closer nucleus
-positive nuclear charger outweighs the negative charge every time an electron is removed
-as the distance of each electron to the nucleus decreases, nuclear attraction increases, causing ionisation energy to increase

Question 6

Draw ionisation graph for nitrogen (7)

Answer 6

graph

Question 7

Ionisation energy trend across period

Answer 7

-general increase because:
-higher nuclear charge as more protons
-electrons added to same shell, which is drawn closer to nucleus
-same number of inner shells, so no change in shielding

Question 8

8 elements that don’t follow ionisation energy trend

Answer 8

Be-> B and Mg-> Al
-both decrease in ionisation energy even though they’re further along period
-this is because B and Al have their outer electron in a P orbital whereas Be and Mg outer electron is in an S orbital
-P orbitals have higher energy and therefore further from the nucleus
-this therefore decreases nuclear attraction, meaning lower ionisation energy
N->O P->S decrease ionisation energies even though they’re along the period
-because in N and P, each p orbital only contains one electron
-in O and S, the p orbital has 2 electron in = spin paired
-spin paired electrons experience some repulsion and therefore are easier to remove

Question 9

Ionisation energy trends down a group

Answer 9

-first ionisation energies decrease
-more shells, so more shielding
-larger atomic radius
-nuclear charge increases, but its effects are outweighed by atomic radius and shielding

Question 10

Metallic bonding

Answer 10

electrostatic forces of attraction between positive ions and delocalised electrons

Question 11

Giant metallic lattice structure

Answer 11

-delocalised electrons spread throughout
-electrons free to move
-over whole structure, charges balance

Question 12

Properties of giant metallic lattices

Answer 12

-high MP and BP- attraction between ions and electrons are very strong so high temp required to overcome electrostatic forces
-electrical conductors- delocalised electrons free to move and can carry charge
-ductile- can be drawn out/ stretched eg. wires
-malleable- can be hammered into different shapes

Question 13

Types bonding across elements in period 2 + 3

Answer 13

Giant metallic:
-Li, Be
-Na, Mg, Al
Giant covalent
-B, C
- Si
Simple molecular
-N2, O2, F2, Ne
-P4, S8, CL2, Ar

Question 14

Trend melting points in metals

Answer 14

-across the period, MP increases
-this is because ionic charge increases, ionic size decreases
-therefore attraction between ions and electrons increase, so more energy required to disrupt the lattice

Question 15

Group 2 properties

Answer 15

-high MP + BP
-light metals, low densities
-white compounds

Question 16

Reaction group 2 element and O2 eg. Ca

Answer 16

2M + O2 -> 2MO
2Ca + O2 -> 2CaO

Question 17

Reaction group 2 elements and H2O eg. Ca

Answer 17

M + 2H2O -> M(OH)2 + H2
Ca + 2H2O -> Ca(OH)2 + H2

Question 18

Reaction group 2 elements and dilute acid eg. Ca + HCl

Answer 18

M + 2HCl-> MCl2 + H2
Ca + 2HCl -> CaCl2 + H2

Question 19

Group 2 oxide + H2O

Answer 19

MO + H2O -> M(OH)2
CaO + H2O -> Ca(OH)2

Question 20

Solubility of group 2 hydroxides

Answer 20

-solubility of hydroxides increase down the group
-this is because they release more OH-
-therefore alkalinity increases down the group
-Be(OH)2 = insoluble
-more soluble= less likely to form precipitate

Question 21

Uses group 2 compound

Answer 21

Ca(OH)2
- neutralise soils by reducing acidity
Mg(OH)2
-used in indigestion tablets by neutralising excess stomach acid
CaCO3
-used in limestone and marble
-drawback as it readily reacts with acid, rainwater is slightly acidic so therefore erodes over time

Question 22

Trend BP of halogens

Answer 22

-Bp increases down the group
-down group physical state changes from gas to liquid to solid (F2 + Cl2= gas, Br2= liquid, I2 + At2= solid)
-this is because each elment has an extra shell of electrons leading to stronger london forces between molecules

Question 23

Halogen REDOX reactions

Answer 23

-Cl2 can oxidise Br- and I- ions
-Br can only oxides I-

Question 24

Colour of halogen in water

Answer 24

Cl2= pale green
Br2= orange
I2= brown

Question 25

Colour of halogen in cyclohexane

Answer 25

Cl2= pale green
Br2= orange
I2= violet

Question 26

Disproportionation-

Answer 26

reaction where the same element is both oxidised and reduced
eg. Cl2 + H2O -> HClO + HCl

Question 27

Formation bleach

Answer 27

Cl2 + 2NaOH -> NaCl + NaClO + H2O

Question 28

CO3 2- test

Answer 28

-add dilute strong acid eg. H2SO4
-collect any gas and bubble through limewater
-should fizz as CO2 produced
-CO2 turns limewater cloudy

Question 29

SO4 2- test

Answer 29

-add dilute HCl and BaCl2
-white ppt

Question 30

Halide ions test

Answer 30

-dissolve suspected halide in water
-add silver nitrate
-add ammonia if can’t distinguish colour
-Cl- = white ppts, soluble in dilute NH3
-Br- = cream ppt, soluble in conc NH3
-I- = yellow ppt, insoluble in NH3

Question 31

NH4+ test

Answer 31

-add NaOH and heat gently
-test any gas with red litmus paper
-ammonia turns red litmus paper blue