3.1.1 Atomic structure

Question 1

Developing the idea of the atom

Answer 1

1661 - boyle proposed no substances smaller
1803 - dalton elements composed of spheres called atoms
1897 - JJ thompson - electrons
1911 - rutherford small pos nucleus in the middle
Gold foil experiment
Fire alpha radiation at gold foil
5. 1913 - bohr electrons in shell6. 1932 - chadwick discovers the neutron

Question 2

Forces in the nucleus

Answer 2

Strong nuclear forces - protons and neutrons together

Electrostatic forces - electrons and protons

Question 3

Uses for the scientists model

Answer 3

Daltons model - explain the geometry of crystals
Bohr’s model - ionic and covalent
Electrons orbiting in shells - bonding

Question 4

TOF Mass spectrometer

Answer 4

Used to find out relative atomic masses
Mass spectra identify different isotopes that make up an element
Happens in a vacuum
1. Vaporization
dissolved in a volatile solvent
2. Ionization
2.. Acceleration
3. Ion drift
4. Detection
5. Data analysis
Signal passed to a computer which generates mass spectra

Question 5

High resolution mass spectrometry

Answer 5

Atomic masses up to 5dp
Low resolution - 1dp

Question 6

What is the m/z value

Answer 6

Mass / charge ratio

Question 8

TOF electrospray ionization

Answer 8

• Electrospray Ionisation
  o This method is used for substances which have a higher molecular mass
  . fragmentation is unlikely to happen
  o For this method, the sample is dissolved in a volatile solvent
  o The solvent is injected into the mass spectrometer using a hypodermic needle
   This produces a fine mist or aerosol
  o The needle is attached to a high voltage power supply, so as the sample is injected, the particles are ionised by gaining a proton from the solvent
  X (g) + H+ → XH+ (g)

Question 9

Using mass spectrometer to calculate relative atomic mass of an element

Answer 9

= (abundance x m/z) + (abundance x m/z) / 100

Question 10

Electron configuration

Answer 10

Shell - subshell - orbits

Question 11

4s, 3d

Answer 11

4s is a lower energy than 3d - so fills first

Question 12

Electrons into atomic orbitals Rules

Answer 12

Atomic orbitals of lower energy are filled first
Orbitals fill singularly before doubling up - as they repel each others in orbitals
No orbitals more than two electrons

Question 13

Ionization energy

Answer 13

The energy required to remove a mole of electrons from a mole of atoms in gaseous state
Measured in KJmol-1
Elected by
Shielding
Atomic charge
Atomic size

Question 14

Succession ionization energies

Answer 14

first electron - needs the least energy to remove it as being removed from a neutral atom
Second electrons - need more energy as removed from a 1+ ion
And so on
come from the 4s before the 3d as more shielding so takes less energy

Question 15

Trends in ionization energies down a group

Answer 15

Decreases
Ar increases
Shielding

Question 16

Trends in ionisation energy along a period

Answer 16

Increases across
More protons increased nuclear charge
Shielding is similar across

Question 17

Ionization energy exceptions

Answer 17

Aluminium - slightly higher energy in subshell - slightly further from the nucleus than in magnesium
Sulphur - electron repulsion - taken from full orbital - repel less energy needed - shielding the same

Question 18

Anomalies in energy level diagrams

Answer 18

Chromium + copper - half full 4s - creates a more stable half full orbital

Question 19

the ion that reaches the detector first in TOF

Answer 19

make sure to write charge the lightest m/z

Question 20

medical use for magmesium hydroxide

Answer 20

intergrestion relife

Question 21

Sub atomic particles

Answer 21

Protons - 1, +1
Electrons -1 , 1/2000
Neutrons 1,0

Question 22

Proton number and mass number

Answer 22

Protons in the nucleus is called the atomic number
Number of protons + number of neutrons

Question 23

Isotopes

Answer 23

Same number of protons and same number of electrons different number of neutrons
React chemically the same way - same el
ectron configuration
Vary in mass number

Question 24

Electron shells

Answer 24

2,8,8,18

Question 25

Stage 2: Acceleration

Answer 25

Stage 2: Acceleration
* They are all accelerated to have the same kinetic energy
o This is important for you to remember when completing calculations
* Since all 1+ ions will have the same kinetic energy, their velocity will depend on their mass
o Lighter ions will move faster and heavier ions will move slower

Question 26

Stage 3: Ion Drift (in the flight tube)

Answer 26

 The 1+ ions will pass through a hole in the negatively charged plate and move into a flight tube

Question 27

Stage 4: Detection

Answer 27

• Once they have pass through the mass spectrometer, the 1+ ions will hit a negatively charged ‘detector’ plate
• As they hit this electric plate, they gain an electron
• This gaining of an electron discharges the ion, and causes a current to be produced
  o This size of the current is proportional to the abundance of those ions hitting the plate and gaining an electron

Question 28

TOF electron impact ionization

Answer 28

Electron Impact Ionisation
* This method of ionisation is used for elements and substances which have a lower molecular mass
* The sample is vaporised and then bombarded with high energy electrons
* The electrons are ‘fired’ from an electron gun
o The electron gun is a hot wire filament which emits electrons as a current runs through it
* As the sample is bombarded by these electrons, an electron is knocked off each particle, forming a 1+ ion

Question 29

peaks on a TOF graph

Answer 29

• The peak with the highest mass is the molecular ion peak, M+, and the peak which has the largest abundance (tallest peak) is called the base peak