Atomic Structure

Question 1

What is the realtive mass of…?

1. Proton
2. Neutron
3. Electron

Answer 1

1. 1
2. 1
3. 1/2000 (becasue this mass is very small you would usually ignore it)

Question 2

What takes up most of the volume of the atom?

Answer 2

Electron orbitals

Question 3

What is an ion?

Answer 3

An atom with a different number of protons and electrons. A neutral aton will have the same number of protons and electrons.

Question 4

What makes an ion negative?

Answer 4

Negative ions have more electrons

Question 5

What makes an ion postive?

Answer 5

Postive ions have less electrons

Question 6

What is an isotope?

Answer 6

Isotopes are atoms of the same element with different numbers of neutrons.

Question 7

What decides the chemical properties of an element?

Answer 7

The number and arrangement of electrons decide the chemical properties of an element.

Question 8

Do isotopes have the same chemical properties? Why?

Answer 8

Yes. Isotopes have the same configuration of electrons, so they have the same chemical properties.

Question 9

Do isotopes have the same physical properties (density, rate of diffusion etc.)? Why?

Answer 9

No. Isotopes have different physical properties as physcial properties tend to depend on the mass of the atom.

Question 10

What’s the relative mass of an atom?

Answer 10

The realtive mass is the mass of an atom compared to Carbon-12

Question 11

What are the steps in mass spectrometry?

Answer 11

1. Vaporisation
2. Ionisation
3. Accelleration
4. Ion Drift
5. Detection
   (Revision guide = different satges to notes)

Question 12

Explain the vaporisation and ionisation stages in mass spectrometry

Answer 12

The sample is vaporised and pushed through a small nozzle at a high pressure. A high voltage is applied, causing the particles to lose an electron and become positive ions.
This is called electrospray ionisation.

Question 13

Explain the accelleration stage in mass spectrometry

Answer 13

The positive ions are accellerated by an electromagnetic field.
Ions with a lower m/z ratio experience a greater accelleration.

Question 14

Explain the ion drift stage in mass spectrometry

Answer 14

When the ions leave the electromagnetic field they have a constant speed and kinetic energy. They ebeter a region with no electric field and so they drift.
Ions with a lower m/z ratio drift at higher speeds.

Question 15

Explain the detection stage of mass spectrometry

Answer 15

Ions that have a lower m/z ratio travel at higher speeds in the dirft region and reach the detector in less time than ions with a higher m/z ratio.
The detector detects charged particles and a mass spectrum is produced.

Question 16

What is plotted on a mass spectrum?

Answer 16

m/z (x-axis) plotted againt abundance (y-axis)

Question 17

How can you work out the Ar from a mass spectrum?

Answer 17

1. Measure the abundance and the m/z ratio
2. Multiply these two values together
3. Add up the totals
4. Divide by the sum of the abundances.

Question 18

How do you get a mass spectrum for a molecular sample?

Answer 18

1. A molecular ion M+ is formed in the mass spectrometer when one electron is removed from the molecule
2. This gives a peak in the spectrum with an m/z ratio equal to the Mr of a molecule
3. This can be used to identify an unknown compound

Question 19

What is the principal quantum number?

Answer 19

The principal quantum number represents relative overall energy of an electron orbital.
The further a shell is from the nucleus the higher its energy and the larger the principal quantum number.

Question 20

What are sub-shells?

Answer 20

Shells are divided up into sub-shells that have slightly different energies .
Sub-shells have different numbers of orbitals which can each hold up to 2 electrons which spin in opposite directions.

Question 21

How do you work out electron configurations?

Answer 21

1. Electrons fill up the lowest energy sub-levels first
2. The ‘4s’ sub-shell has a lower energy level than the ‘3d’ sub-shell.
3. Electrons fill orbitals orbitals singularly before the start sharing
4. To make ions from the ‘s’ and ‘p’ block of the periodic table, remove/add from the higher occupied shell.

Question 22

How do Cromium and Copper behave?

Answer 22

Cromium and Copper donate one of their electrons to the ‘3d’ sub-shell before they fill up the ‘4s’ shell (ie. ‘4s’ will only have one electron in)
This is ecasue they are happier with a more stable full or half-full d sub shell.

Question 23

How do transition metals behave?

Answer 23

When transition metals become ions they lose their 4s electrons before their 3d ones.

Question 24

What is the first ionisation energy?

Answer 24

The energy needed to remove one one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions.

Question 25

Is the process endo or exothermic?

Answer 25

Becasue you are putting in energy to ionise an atom, it is an endothermic process.

Question 26

The lower the ionisation energy...

Answer 26

the easier it is to form an atom

Question 27

What 3 factors affect ionisation energy?

Answer 27

1. Nuclear Charge (total charge of protons in the nucleus) 2. Distance from nucleus 3. Sheilding

Question 28

How does the nuclear charge affect ionisation energy?

Answer 28

The more protons there are in the nucleus, the more positively charged the nucleus is and the stronger the attraction for the electrons so the harder they are to remove and the HIGHER the ionisation energy

Question 29

How does the distance from the nucleus affect the ionisation energy?

Answer 29

Attraction lowers very rapidly the further away electrons are from the nucleus. So the CLOSER an electron is to the nucleus the HIGHER the ionisation energy.

Question 30

How does sheilding affect the ionisation energy?

Answer 30

As the number of electrons between the outer electrons and the nucleus increases, the outer elecrons feel less attraction towards the nuclear charge. This lessening of the pull of the nucleus by inner shells of electrons is called shielding. The LOWER the sheilding the HIGHER the ionisation energy.

Question 31

What dooes a high ionisation energy mean?

Answer 31

A high IE means that there's a high attraction between the electron and the nucleus and so more energy is needed to remove the e-

Question 32

What are successive ionisation energies?

Answer 32

Successive ionisation energy is the energy needed to remove n electron from each atom in 1 mole of gaseous atoms to from 1 mole of gaseous n+ ions.