atomic structure

Question 1

explain why the first ionisation energy of Mg is higher than Na

Answer 1

higher nuclear charge; same shielding; so electron is more attracted to nucleus

Question 2

explain why N atoms are larger than O atoms

Answer 2

less nuclear charge; same shielding; so electrons less attracted to nucleus

Question 3

explain the difference in size between a calcium ion and a calcium atom

Answer 3

ion loses its outer shell; and nuclear charge is spread between less electrons; so ion is smaller

Question 4

why does 1st ionisation energy go down from Mg to Al

Answer 4

Al electrons are removed from a higher energy level; this has greater effect than the increase in nuclear charge

Question 5

why does 1st ionisation energy go up from Al to Si

Answer 5

Si has higher nuclear charge; same shielding; (and smaller atomic radius)

Question 6

why does 1st ionisation energy increase across a period

Answer 6

nuclear charge increases; shielding stays the same; (atomic radius decreases)

Question 7

why does 1st ionisation energy go down from P to S

Answer 7

S has a p orbital with a pair of electrons inside; paired electrons are easier to remove as they repel each other

Question 8

explain polarisation in an ionic substance

Answer 8

anion’s electron cloud becomes distorted; because of attraction to the cation; so bonding has some covalent character

Question 9

explain why polarisation occurs in magnesium iodide but not sodium iodide

Answer 9

Mg 2+ has higher charge and smaller ionic radius; so anion’s electron cloud is more attracted

Question 10

state how thermochemical data can be used to show that there is polarisation in an ionic substance

Answer 10

theoretical and experimental lattice energies will be different

Question 11

explain the term periodicity

Answer 11

the repeated trend across each period

Question 12

what is first ionisation energy

Answer 12

energy to remove one electron each from one mole of gaseous atoms of an element

Question 13

why does 1st ionisation energy go down from Kr to Rb

Answer 13

Rb electrons are removed from a higher energy level; more shielding

Question 14

what are isotopes

Answer 14

atoms with the same number of protons but different numbers of neutrons

Question 15

what is relative atomic mass

Answer 15

weighted avg atomic mass of one atom of an element compared to 1/12 of a carbon 12 atom

Question 16

what is an orbital

Answer 16

region in an atom that can hold 2 electrons of opposite spin