Physical - Atomic Structure

Question 1

describe the plum pudding model

Answer 1

sphere of positive charge with small negative charges distributed within

Question 2

which fundamental particles exist in the nucleus, giving it what charge?

Answer 2

protons and neutrons
positive

Question 3

what is the relative mass of an electron?

Answer 3

1/1840

Question 4

what must happen to each electron shell before the next one holds any electrons?

Answer 4

it must fill

Question 5

state the formula for calculating the maximum number of orbiting electrons held by a shell

Answer 5

2(n²)

Question 6

what is mass number? what letter represents it?

Answer 6

sum of protons and neutrons in an atom
A

Question 7

what is atomic number? what letter represents it?

Answer 7

the number of protons in an atom
Z

Question 8

what is the definition of relative atomic mass?

Answer 8

the mean mass of an atom of an element, divided by 1/12 of the mean mass of a atom of carbon-12

Question 9

why is Mr the mean mass of an atom of an element, divided by 1/12 of the mean mass of a atom of carbon-12?

Answer 9

because it takes the relative abundances of the different isotopes of an element into account

Question 10

what are isotopes?

Answer 10

atoms of the same element with the same atomic number (same protons and electrons) but with a different mass number (different neutrons)

Question 11

what kind of isotopes react in the same way? why?

Answer 11

neutral isotopes
their atomic number and electron configuration is the same

Question 12

what properties are different between isotopes? why?

Answer 12

physical properties
due to the different mass number

Question 13

how are ions formed?

Answer 13

when an atom loses or gains an electron so it has an overall charge

Question 14

what does time of flight (TOF) mass spectrometry assess?

Answer 14

the time it takes for ions of each isotope to reach a detector

Question 15

what are the five main stages of TOF mass spectrometry?

Answer 15

ionisation
acceleration
ion drift
detection
analysis

Question 16

what can mass spectrometry be used for?

Answer 16

To establish relative isotopic mass and relative abundance of isotopes
Identify elements
Determine relative molecular mass

Question 17

In TOF mass spectrometry, describe the process of ionisation

Answer 17

sample of an element is vapourised and injected into the mass spectrometer where a high voltage is passed over the chamber, leaving +1 ions in the chamber

Question 18

In TOF mass spectrometry, describe the process of acceleration

Answer 18

the positively charged ions are accelerated towards a negatively charged detection plate so they all have the same kinetic energy

Question 19

In TOF mass spectrometry, describe the process of ion drift

Answer 19

Ions enter a region with no electric field so they drift through
Lighter ions drift faster than heavier ones

Question 20

In TOF mass spectrometry, describe the process of detection

Answer 20

As lighter ions travel at higher speeds in the drift region, they reach the detector in less time than heavier ones
The detector detects charged particles and a mass spectrum is produced

Question 21

In TOF mass spectrometry, describe the process of analysis

Answer 21

Mass spectrum is plotted
This plots mass/charge against abundance

Question 22

what are orbitals?

Answer 22

clouds of negative charge that hold electrons

Question 23

what are the first three orbitals?

Answer 23

s
p
d

Question 24

what is the shape of the s-orbital?

Answer 24

spherical

Question 25

what is the shape of the p-orbital?

Answer 25

dumbbell

Question 26

how many electrons can an s-orbital hold before the next one is filled?

Answer 26

2

Question 27

how many electrons can a p-orbital hold before the next one is filled?

Answer 27

6

Question 28

how many electrons can a d-orbital hold before the next one is filled?

Answer 28

10

Question 29

why are orbitals filled in the order s → p → d?

Answer 29

because the energy of the orbitals increases in this order

Question 30

in terms of spin, how do electrons pair up?

Answer 30

electrons with opposite spin

Question 31

which energy orbital is filled first?

Answer 31

the lowest energy one

Question 32

what is the maximum number of electrons a single orbital can hold?

Answer 32

2

Question 33

what is the definition of ionisation energy?

Answer 33

the minimum energy required to remove one mole of electrons from on mole of atoms in a gaseous state

Question 34

why do successive ionisation energies typically require more energy than the first?

Answer 34

because as electrons are removed the electrostatic attraction between nucleus and outer electrons increases

Question 35

what is the trend in first ionisation energies along a period?

Answer 35

increases due to decreasing atomic radius and so greater electrostatic forces of attraction

Question 36

what is the trend in first ionisation energies down a group?

Answer 36

decreases due to increasing atomic radius and shielding which reduces the effect of electrostatic forces of attraction

Question 37

when successive ionisation energies are plotted on a graph, what does a sudden large increase indicate?

Answer 37

a change in energy level

Question 38

when successive ionisation energies are plotted on a graph, why is there a large sudden increase at a change in energy level?

Answer 38

because the electron is being removed from an orbital closer to the nucleus, which requires more energy, since the electrostatic force is stronger

Question 39

what does the large increase in ionisation energy at a change of energy level provide evidence for?

Answer 39

atomic orbital theory

Question 40

why is the first ionisation energy of aluminium lower than expected?

Answer 40

due to a single pair of electrons with opposite spin so there is natural repulsion, reducing the amount of energy needed to remove the outer electron