Module 2: Foundations in Chemistry Flashcards
Define relative molecular mass.
The mass of that specific molecule, relative to the mass of 1/12 of a carbon-12 atom.
Define relative atomic mass.
The weighted average mass of an atom of an element taking into account all of its naturally occurring isotopes relative to the mass of 1/12 of a carbon atom.
Why is the mass of an atom not proton+neutron+electron?
Due to the strong nuclear force holding protons and neutrons together, some mass is lost, and this is called mass defect.
What is the empirical formula of a compound?
The simplest whole number ratio of atoms present in a molecule of a compound.
What is the ideal gas equation?
PV=nRT
Define oxidation number.
The number of electrons involved in bonding an element to another.
What is the oxidation number of an element?
0
What are the oxidation number exceptions?
- Hydrogen in metal hydrides: -1
- Oxygen in peroxides: -1
- Oxygen when bonded to fluorine: +2
Define disproportionation.
When a single element is both oxidised and reduced in a reaction.
How many electrons does an orbital hold?
Two, which spin in opposite directions.
What are the exceptions when writing electron configuration?
- 4s is filled before 3d, because it has less energy, however it also loses electrons before 3d.
- For chromium and copper, the 4s sub-shell only has one electron while the 3d sub-shell has five and ten electrons respectively. This is because this is more stable.
What is the shape of an S sub-shell and a P sub-shell?
- S: Spherical
- P: Dumbbell shaped
Which elements don’t follow the octet rule?
- Boron 8 >
- Sulfur 8 <
Define coordinate / dative covalent bonding.
When one atom provides both electrons in a covalent bond.
How does solubility change as ionic charge increases?
It decreases.
