Atomic Structure

Question 1

Describe the Bohr Model

Answer 1

Protons and electrons are found in the nucleus
Electrons orbit around the nucleus in shells / energy levels

Question 2

What is the relative mass of a proton, neutron and electron?

Answer 2

proton = 1
neutron = 1
electron = 1/1840

Question 3

What is the relative charge of a proton, neutron an electron?

Answer 3

proton = +1
neutron = 0
electron = -1

Question 4

define atomic number

Answer 4

the number of protons in the nucleus

Question 5

define mass number

Answer 5

total number of protons and neutrons in the nucleus

Question 6

define isotopes

Answer 6

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

Question 7

why do isotopes of the same element have the same chemical properties?

Answer 7

they have the same electron configuration

Question 8

define ionisation energy

Answer 8

the amount of energy needed to remove one mole of electrons from one mole of atoms, in the gaseous state

Question 9

what are the units of ionisation energy?

Answer 9

kJ mol-1

Question 10

what three factors influence ionisation energy?

Answer 10

nuclear charge
distance from the nucleus
shielding

Question 11

why is the second ionisation energy higher than the first?

Answer 11

second electron removed from an ion that already has a positive charge

Question 12

what is an orbital?

Answer 12

a region within an atom that can hold up to two electrons with opposite spins

Question 13

what is the highest energy electron?

Answer 13

outermost electron on an atom/ion

Question 14

why is the outermost electron the highest energy electron?

Answer 14

it is the furthest from the nucleus

Question 15

when are d-block elements more stable?

Answer 15

when they have a full, or exactly half full subshell

Question 16

what is the electron configuration of chromium?

Answer 16

1s2 2s2 2p6 3s2 3p6 4s1 3d5

Question 17

what is the electron configuration of copper?

Answer 17

1s2 2s2 2p6 3s2 3p6 4s1 3d10

Question 18

how does the ionisation energy change down a group?

Answer 18

atoms get bigger
more shielding
weaker attraction between nucleus and electron in outer shell
ionisation energy decreases down group

Question 19

state and explain the trend in atomic radius down a group

Answer 19

atomic radius increases
outer electrons are further away from nucleus, so they are less attracted to the nucleus

Question 20

why does the atomic radius get smaller from left to right across a period?

Answer 20

nuclear charge increases
greater attraction between the electrons and nucleus
amount of shielding stays the same

Question 21

what two factors does the mass spectrometer measure?

Answer 21

relative abundance
mass/charge ratio

Question 22

why are sample particles ionised in the mass spectrometer?

Answer 22

so they can be accelerated towards the negatively charged plate
so they generate a current when the hit a detector

Question 23

how is the ion accelerated in the mass spectrometer?

Answer 23

positive ions attracted to the negatively charged plate
all ions have the same kinetic energy

Question 24

how are ions separated in the flight tube in the mass spectrometer?

Answer 24

ions travelling at higher speeds (small m/z) move ahead of those travelling more slowly (large m/z)

Question 25

how are the ions detected in the mass spectrometer?

Answer 25

each ion hits the detector ion gains an electron generates a current size of the current is proportional to the abundance of the ion1

Question 26

describe electron impact

Answer 26

sample is vaporised high energy electrons fired at it from an electron gun knocks off an electron forming +1 ion

Question 27

describe electrospray ionisation

Answer 27

sample dissolved in volatile solvent injected through fine hypodermic needle attached to the positive terminal of a high voltage power supply particles ionised by gaining a proton

Question 28

how do you calculate the Ar from mass spectrometry?

Answer 28

((mass 1 x abundance 1) + (mass 2 x abundance 2) + (mass n + abundance n)) / total abundance

Question 29

what is the equation for calculating kinetic energy of ions in the mass spectrometer?

Answer 29

KE = 1/2 x m x v^2

Question 30

what are the units for KE = 1/2 x m x v^2 and d = t x v

Answer 30

KE = J m = Kg V = m s-1 d = m t = s

Question 31

how do you calculate the mass of an atom, in kg, using Avogadro's constant?

Answer 31

mass number / 1000 / 6.022 x 10^23