2. Atomic structure

Question 1

number of protons in an atom=

Answer 1

number of electrons

Question 2

isotopes are different atoms of the same element with different

Answer 2

mass numbers (neutrons)

Question 3

isotopes have the same … properties but different … properties

Answer 3

same chemical
different physical

Question 4

relative atomic mass Ar is the

Answer 4

average of the masses of the isotopes in a naturally occurring sample of the element relative to the mass of 1 of an atom of carbon-12

Question 5

electrons fill the … energy levels first

Answer 5

lower

Question 6

in emission spectrum, lines converrge at

Answer 6

high frequency / high energy

Question 7

how is the emission spectrum formed?

Answer 7

1. with the help of an electric discharge, electron is promoted to a higher energy level
2. electron is unstable and will fall to a lower energy level
3. energy is given out in the form of light

Question 8

aufbau principle

Answer 8

electrons fill sub-levels from the lowest energy level upwards – this gives the lowest possible (potential) energy

Question 9

the 4s sub-level is lower in energy than the

Answer 9

3d sub-level

Question 10

an orbital is a region of space where

Answer 10

there is a high probability of finding an electron
represents a discrete energy level

Question 11

an orbital contains maximum … electrons

Answer 11

2

Question 12

orbitals with same energy

Answer 12

degenerate

Question 13

pauli exclusion principle

Answer 13

opposite spin

Question 14

hund’s rule

Answer 14

electrons fill degenerate orbitals. so as to give the max number of electrons with the same spin

→ this is why we have arrows going in the same direction

Question 15

ionisation energy

Answer 15

the minimum amount of energy required to remove an electron from a gaseous atom

Question 16

E =

Answer 16

hv = hc/λ

Question 17

first ionisation energy

Answer 17

energy required to remove one electron from. each atom in one mole of gaseous atoms under standard conditions

Question 18

ionisation energy … across a period

Answer 18

increases
increase in effective nuclear charge felt by outer electron

Question 19

exceptions to the trend in ionisation energy across a period:

Answer 19

boron ionisation energy is lower than beryllium
→ 2p sub-level is higher in B, therefore easier to remove than from Be

first IE of oxygen is lower than for nitrogen

Question 20

in transition metals, 4s electrons are always removed before the

Answer 20

3d
even if sub levels are filled in order 4s the 3d