3.1.1 Atomic Structure

What are the 4 orbitals?

S, P, D and F

How many pairs are in an S orbital

1

How many pairs in a P orbital

3

How many pairs in a D orbital

5 pairs

How many pairs in a F orbital?

7 pairs

what orbital comes first 3D or 4S

4S

define ionisation energy

energy required to remove 1 mol electrons from 1 mol gaseous atoms to form 1 mol gaseous unipositive atoms

What four things impact ionisation energy

atomic radius, nuclear charge, shielding, orbital pairs

what trends do ionisation energies have (3)

decrease down groups, increase across period, change in shell

What is the first ionisation energy equation for Al

Al(g)  —>   Al⁺(g) + e^-

What is the second ionisation energy equation for Al

Al⁺(g)     Al²⁺(g) + e^-

atomic number

number of protons

atomic mass

number of protons and electrons

relative isotopic mass

mass of an isotope relative to 1/12th a carbon-12 atom

isotope

an atom with the same number of protons and electrons but a different number of neutrons

relative atomic mass

mass of an atom relative to 1/12th a carbon-12 atom

relative molecular mass

sum of all the molecules relative atomic masses in a compound

what is the charge of an electron

-1

what is the charge of a proton

+1

what is the charge of a neutron

0

what is the mass of an electron

1/2000

what is the mass of a proton

1

what is the mass of a neutron

1

What are the uses of mass spectrometry

• (atoms/elements) isotopic mass / abundance, Ar

• (Compounds) identifies unknown compounds, Mr

Describe electron impact ionisation

1. Sample vapourised

2. Electrons fired at high speed

3. Electrons knocked off

4. Positive ions attract to a metal plate where acceleration occurs

What is the equation for electron impact ionisation

X(g) + e- —> X+(g) + 2e-

What is electron impact ionisation used for

Low Mr substances, fragmentation

Describe electro spray ionisation

1. Sample dissolved in volatile solution

2. Injected via a mist into a hyperdermic needle

3. Needle is attached to a positive high voltage

4. Gains a proton from a solvent

5. Solvent evaporates

6. Positive ion attracts to metal plate and accelerates

What is the equation for electro spray ionisation

X(g) + H+ —> XH+(g)

What is electro spray ionisation used for

High Mr

Describe what happens in the flight tube

1. Positive ions accelerate gaining kinetic energy

2. Smaller particles are faster than bigger ones

What is the equation for kinetic energy

½ mv² = KE

What is the equation for the mass of one ion

(Relative isotopic mass) x10^-3 / 6.022×10²³

Describe how detection occurs

1. Positive ions on a negative plate create a current

2. Current size is proportional to number of ions

What is the equation for velocity

V = distance / time

How do you find the Mr in electron impact ionisation

last main spike is Mr, rest are fragments

How do you find the Mr in electro spray ionisation

Penultimate peak is the Mr, the last peak is the H+