inorganic chemistry

principal quantum number, n

indicates the main energy level for an electron and is related to the size of the orbital

the angular momentum quantum number, l

determines the shape of the subshell and can have values from zero to n −1

convergence limit

energy needed for electrons to break away from the hydrogen atom

emission spectroscopy

light of a specific wavelength/frequency is emitted as excited electrons drop down from higher energy levels to a lower energy level.

absorption spectroscopy

light of a specific wavelength is absorbed and electrons are promoted to higher energy levels.

magnetic quantum number, mₗ

describes the orientation of orbitals of the same shape. 3 possible p-orbitals, +1,0,-1. 5 possible d-orbitals, +2, +1, 0, -1, -2

spin quantum number, mₛ

each orbital can hold up to 2 electrons. only two values +1/2 and -1/2

s- orbitals

spherical in shape

p-orbitals

dumb-bell shape

d-orbitals

l=2

degenerate

having equal energy

exceptions of incomplete d sub-shells in transition metals

Zn²⁺ and Sc³⁺

Aufbau Principle

electrons fill orbitals in order of increasing energy

Hund's Rule

when degenerate orbitals are available, electrons fill each singly, keeping their spins parallel.

Pauli Exclusion Principle

no two electrons in the same atom can have the same set of four quantum numbers

why is the first ionisation energy of boron slightly lower than that of beryllium?

beryllium has a full 2s sub-shell, which is relatively stable. Boron has a single 2p electron, which is less stable as it a part-filled orbital, is shielded from the nucleus by the electrons in the 2s orbital and so requires less energy to remove this single electron from the p sub-shell.

first ionisation energy

The energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions

why is the first ionisation energy of nitrogen higher than that of oxygen

half filled sub-shells are relatively stable and it is easier to remove the fourth p electron from the 2p shell of oxygen. The fourth electron in the 2p orbital leads to electron- electron repulsion, which lowers the attraction between the nucleus and the fourth electron.

why do transition metals exhibit variable oxidation states?

they can not only lose their 4s electrons but also some or all of their 3d electrons

why do Fe²⁺ ions turn into Fe³⁺ ions?

the Fe³⁺ ions form in preference because of the extra stability associated with all the d-orbitals being half-filled

Rules of oxidation states

Simple ions such as K⁺, Na⁺, Cl⁻ continue to count as +1 or -1. Oxygen is always assumed to be 2-. Hydrogen is always assumed to be -1. Overall charge on a neutral compound is always 0. In polyatomic atoms, the sum of all the oxidation numbers is equal to the overall charge on the ion.

compounds containing metals in a high oxidation state tend to act as?

oxidising agents

compounds containing metals in low oxidation states tend to act as?

reducing agents

ligands

ion, atom or molecule that contains at least one lone pair of electrons.

monodentate ligands

can only form one dative bond with a metal atom/ion

Bidentate ligand

can form two bonds with the metal atom/ion.

hexadentate ligand

form 6 bonds with the metal atom/ions

coordination number

number of bonds formed between the metal ion and the ligands in the complex ions

cation

A positively charged ion

Anion

A negatively charged ion

which ligands have no charge

carbon monoxide, water, ammonia

which ligands have a -1 charge

hydroxide, cyanide, chloride

which ligands have a -2 charge

oxide, oxalate

lone pairs

Electrons not involved in bonding.

what shape has 2 bonding pairs of electrons?

linear

what shape has 3 bonding pairs of electrons?

trigonal planar

what shape has 2 bonding pairs and 2 non bonding pairs of electrons?

angular

what shape has 4 bonding pairs of electrons?

tetrahedral

what shape has 4 bonding pairs and 2 non bonding pairs?

square planar

what shape has 3 bonding and 1 non bonding electron pair?

trigonal pyramidal

what shape has 5 bonding pairs?

trigonal bipyramid

what shape has 6 bonding pairs?

octahedral

Repulsive forces between bonding pairs of electrons

The repulsive effect of a non bonding pair is greater than that of a bonding pair

Why are bonding pairs less repulsive

Because they are attracted by two nuclei

The colour of a transition metal is

Complimentary to the absorbed colour

heterogeneous catalyst

Catalyst in a different physical state than the reactants

homogeneous catalyst

Catalyst that is in the same physical state as the reactants

UV-visible spectroscopy

Quantitative method of analysis to determine the concentration and hence the mass of a transition metal in a compound or alloy

standard solution

a solution whose concentration is accurately known