Atomic Structure

Question 1

What is the history of the atom?

Answer 1

1. Robert Boyle - 1661 (chemical elements)
2. John Dalton - 1803 (elements consist of atoms/invisible particles)
3. J J Thomson - 1897 (plum pudding model)
4. Neils Bohr - 1913 (atom is orbited by electrons)
5. Ernest Rutherford - 1911 (most of mass of an atom is in nucleus)
6. Erwin Schrodinger - 1926 (wave equation for electron movement)

Question 2

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

Answer 2

Proton- 1
Electron- 1/1840
Neutron- 1

Question 3

What is the charge of a proton, electron and neutron?

Answer 3

Proton- +1
Electron- -1
Neutron- 0

Question 4

What is the arrangement of sub-atomic particles?

Answer 4

Protons and neutrons are in the centre of the atom, held by a strong nuclear force

Question 5

What is the definition of relative atomic mass?

Answer 5

The average mass of an atom of an element compared to 1/12th the mass of carbon 12.

Question 6

What is an isotope?

Answer 6

An element with the same number of protons but different number of neutrons.

Question 7

Why do isotopes have all the same chemical properties?

Answer 7

They chemically react in the same way because they have the same electron configuration.

Question 8

What is the equation for the number of electrons in each shell?

Answer 8

2n^2 n=number of the shell

Question 9

What is the relative abundance of an isotope?

Answer 9

Percentage of atoms with a specific atomic mass found in a naturally occurring sample of an element.

Question 10

What is the purpose of mass spectrometry?

Answer 10

To find the relative abundance of each isotope of an element.

Question 11

What does a mass spectrometer show?

Answer 11

A series of peaks on a graph with relative abundance of isotopes against mass/charge, this can be used to calculate relative atomic mass.

Mass spectrometry can identify elements

Question 12

What are the conditions required for mass spectrometry to take place?

Answer 12

• In a vacuum, to prevent ions from colliding with air molecules
• Elements in a gaseous state - solids are vaporised

Question 13

What are the 4 stages of mass spectrometry?

Answer 13

1. Ionisation
2. Acceleration
3. Ion drift
4. Detection

Question 14

What occurs in ionisation / what are the two different types?

Answer 14

Electrospray - sample is dissolved in volatile solvent and this causes the addition of a proton

Electron impact - electrons are fired from electron gun at vaporised sample this causes an electron to be knocked off (1+ ion)

Ionisation is where atoms are converted to ions

Question 15

What occurs in acceleration?

Answer 15

Ions are accelerated using an electric field so they have the same kinetic energy

Lighter particles have a higher velocity

Question 16

What occurs in ion drift?

Answer 16

Ions pass through hole in negatively charged plate through flight tube

Question 17

What occurs in detection?

Answer 17

Lighter ions arrive first due to having higher velocities

The more electrons that his the plate the larger the current and the bigger the peak

Question 18

What occurs in data analysis?

Answer 18

Data is recorded in a mass spectrum

Question 19

Why is a negatively charged plate used in mass spectrometry?

Answer 19

To attract positive ions

Question 20

What are the 4 sub-levels? + how many electrons/orbitals do they have/hold?

Answer 20

s- 2 (1 orbital)
p- 6 (3 orbitals)
d- 10 (5 orbitals)
f- 14 (7 orbitals)

Question 21

What is the aufbau principle?

Answer 21

Lowest energy sub-levels are occupied

Question 22

Whats hunds rule of maximum multiplicity?

Answer 22

If two or more orbitals of equal energy are available the electrons will occupy them singly before becoming paired

Question 23

What is the Pauli Exclusion principle?

Answer 23

Two electrons in the same orbital must have opposite spins (up/down arrows)

Question 24

Which elements do not follow the rules of normal electronic configurations?

Answer 24

Chromium, Copper

Question 25

What is coppers electron configuration?

Answer 25

1s2 2S2 2P6 3S2 3P6 4S1 3d10

Question 26

What is chromium electron configuration?

Answer 26

1𝑠2 2𝑠2 2𝑝6 3𝑠2 3𝑝6 4𝑠1 3𝑑5

Question 27

Why do copper and chromium contain one electron in their 4s orbital?

Answer 27

4s and 3d orbitals lie close together in energy, if 3d is half full or completely full is a lower energy arrangement

Question 28

What is ionisation?

Answer 28

Process in which atoms lose of gain electrons and become ions

Question 29

What is the first ionisation energy?

Answer 29

The energy required to remove one electron from one mole of atoms in a gaseous state
It is a measure of strength of attraction between outermost electron and nucleus
M(g) -> M+ (g) + e-

Question 30

What factors affect ionisation energy?

Answer 30

• charge on the nucleus
• distance of electron from the nucleus
• number of electrons between outer electrons and nucleus
• whether electron is paired or alone in its orbital

Question 31

What is the general trend of first ionisation energies of period 3 elements? + why does it have this trend?

Answer 31

Increase in ionisation energy as you move along the period

• number of protons increases
• similar shielding
• atomic radius decreases

Question 32

What are the anomalies in the graph?

Answer 32

First ionisation energy of sulphur is lower than phosphorus even though it is further along the period
This is because they both have their highest energy electron in the 3p orbital but in Sulphur the electron is paired but in Phosphorus each 3p orbital is occupied. Therefore by mutual repulsion between paired electrons means that less energy is required to remove one in Sulphur.

Question 33

What is another anomaly of the graph?

Answer 33

First ionisation of Al is less than Mg this is because the electron removed to ionise Al is in a 3p sub-shell which is of higher energy than the electron removed in the 3s sub-shell to ionise magnesium thus removing an electron from a higher energy orbital requires less energy.

Question 34

What is the second ionisation energy and equation?

Answer 34

The energy required to remove one electron from each ion in 1 mole of gaseous 1+ ions to from 1 mole of gaseous 2+ ions

M+(g) -> M2+(g) + e-

Question 35

Which ionisation energy requires less energy?

Answer 35

First ionisation energy

Question 36

What is the ionisation energy trends in group 2?

Answer 36

decrease in ionisation energy
Going down the group, nuclear charge increases
The positive charge felt by the electron from the nucleus is less than the full nuclear charge because inner electrons shield the nuclear charge