Whcih two factors cause London forces to be strong
A greater number of electrons and an increasing surface contact area (straight chain molecule)
Give three typical properties of liquids that can
High boiling point, high viscosity, high surface tension, unusually low density of ice, broad infra-red spectra absorption.
What drives many ionic compounds to be soluble in
The energy released by the hydration of the ions.
Why are smaller alcohols soluble in water and larg
They can all hydrogen bond with water, but the larger ones have large non-polar (hydrophobic) carbon chains.
What does an oxidising agent do?
Accepts electrons and gets reduced.
What does a reducing agent do?
Donates electrons and gets oxidised.
What is meant by the term disproportionation?
Where the oxidation number of the SAME element both rises and falls in oxidation number.
How does first ionisation energy change down a gro
It gets smaller as the atoms get larger as there are more electron shells and the outer electron becomes further away from the nucleus.
What has to happen for one substance to dissolve i
- Bonds in the substance have to break
- Bonds in the solvent have to break
- New bonds have to form between the substance and the solvent
A substance will only dissolve if the strength of the new bonds formed is about the same as, or greater than, the strength of the bonds that are broken.
How does the solubility of group 2 hydroxides chan
How does the solubility of group 2 sulphates chang
How and why does the stability of group 2 carbonat
It increases as the cations get larger and less polarising.
What causes flame colours to be produced?
Electrons are excited by heat to higher energy levels. When they fall back they release photons of light of fixed energy and colour.
What is thermal decomposition?
Thermal decompsition is when a substance is broken down when heated.
The more thermally stable a substance is, the more heat it will take to break it down.
What would you observe on thermal decomposition of
A brown gas (nitrogen dioxide) and droplets of water at the mouth of the test tube if it is hydrated.