B2 Redox + Periodicity Flashcards
Oxidation number of element
0
Oxidation number of group 1
1+
Oxidation number of group 2
2+
Oxidation number of flourine
1-
Oxidation number of oxygen in H2O2
1-
Oxidation number of hydrogen in H2O2
1+
What substance gets the negative oxidation number in a compound
The most electronegative
Sum of oxidation numbers in a compound
0
Sum of oxidation numbers in an ion
Charge of ion
What happens to oxidation number when a substance is reduced
Decreases
What happens to oxidation number when a substance is oxidised
Increases
When writing systamatic names, when does the Roman numeral oxidation number come
- In brackets after the element
- e.g Titanium (IV) Oxide
In metal and acid reactions, what is reduced and what is oxidised
- Metal oxidised
- Hydrogen reduced
Meaning of oxidation
- Loss of electrons
- Increase in oxidation number
Meaning of reduction
- Gain of electrons
- Decrease in oxidation number
Define Disproportionation
Reduction and oxidation of the same element in the same reaction
Define Oxidising Agent
Takes electrons from the species being oxidised
Define Reducing Agent
Adds electrons to the species being reduced
How to write elemental half-equations
- Calculate overall charge on each side
- Add electrons to more positive side
- Ensure fully balanced
How is the periodic table arranged
Increasing atomic number
How to write half-equations for acidic conditions
- Balance the element changing oxidation state
- For every oxygen, add an H2O to the other side
- For every hydrogen, add an H+ to the other side
- Use electrons to ensure both sides have the same charge
What do elements in periods in the periodic table have
Repeating trends in physical and chemical properties
What do elements in groups of the periodic table have
Similar chemical properties
Define Periodicity
The repeating trends in physical and chemical properties across different periods
How to explain why an element is in the s/d/p block
It’s highest energy electron is in the s/d/p subshell
Define First Ionisation Energy
The energy required to remove 1mol of electrons from 1mol of gaseous atoms
How to explain differences in ionisation energies
- Electron shells
- Atomic radius
- Sheilding
- Nuclear charge
- Sheilding + atomic radius outweigh nuclear charge
- Nuclear attraction
What must always be stated when describing changes in ionisation energies
Sheilding - even if has no effect
When given an ionisation energy graph for an element, how can you tell what group that element is in
- Greatest jump in ionisation energies
- Jump 4 - 5
- In group 4
General equation for first ionisation energy
General equation for second ionisation energy
Draw a graph for ionisation energies across period 2
What element has highest first ionisation energy
Helium
On first ionisation energy graphs, there is a general increase - what are the exceptions
- New shell - decrease
- p subshell - decrease
- group 6 - decrease (new electron in singular paired orbital so more repulsion)
