Unit 1 Glossary

Question 1

absorption spectrum

Answer 1

a spectrum consisting of dark absorption lines superimposed on a bright continuous spectrum. It shows the absorption of radiation by a material over a range of wavelengths.

Question 2

Aufbau principle

Answer 2

this states that orbitals are filled in order of increasing energy.

Question 3

Bidentate

Answer 3

a ligand that contains two atoms with lone pairs of electrons capable of bonding to a metal atom or ion.

Question 4

Complex

Answer 4

a complex consists of a central metal atom or ion surrounded by ligands.

Question 5

Co-ordinate bond

Answer 5

a covalent bond in which one of the atoms supplies both of the electrons of the shared pair.

Question 6

Co-ordination compounds

Answer 6

compounds in which a central metal atom or ion is attached to a group of surrounding molecules or ions by dative covalent bonds (co-ordinate bonds).

Question 7

Co-ordination number

Answer 7

the number of nearest neighbours by which an atom or ion is surrounded in a structure.

Question 8

Dative covalent bond

Answer 8

both the shared electrons originally came from the same atom.

Question 9

Degenerate

Answer 9

a set of atomic orbitals that are of equal energy to each other.

Question 10

Electromagnetic Spectrum

Answer 10

the range of frequencies or wavelengths of electromagnetic radiation.

Question 11

Electronegativity

Answer 11

a measure of the attraction an atom involved in a bond has for the electrons of the bond.

Question 12

Emission spectroscopy

Answer 12

the study of emission spectra produced by exited substances (often gaseous atoms or molecules).

Question 13

Excitation energy

Answer 13

the minimum energy required to change a system from its ground state to a particular excited state.

Question 14

Frequency

Answer 14

The number of wavelengths that pass a fixed point in one unit of time.

Question 15

Ground state

Answer 15

the lowest possible electronic configuration the electrons in an atom can adopt.

Question 16

Heisenberg’s uncertainty principle

Answer 16

this states that it is impossible to state precisely the position and the momentum of an electron at the same instant.

Question 17

Hexadentate

Answer 17

a ligand that bonds to a metal ion using electron pairs on six donor atoms.

Question 18

Hund’s rule

Answer 18

when degenerate orbitals are available, electrons fill each singly, keepings their spins parallel, before pairing starts.

Question 19

Ionisation

Answer 19

The addition or removal of an electron to create an ion.

Question 20

Ionisation energy

Answer 20

The energy involved in removing one mole of electrons from one mole of gaseous atoms.

Question 21

Ligands

Answer 21

Molecules or ions that bond to the central metal atom or ion in a complex.

Question 22

Lone pair

Answer 22

A lone or non-bonding pair of electrons is a pair of outer or valence shell electrons that have opposite spins which are not used to form covalent bonds within the molecule.

Question 23

Molecular orbital

Answer 23

A molecular orbital is a region in space between the nuclei where there is a high probability of finding electrons. It is formed by the overlap of two atomic orbitals.

Question 24

Monodentate

Answer 24

A ligand that bonds to a metal atom or ion using the electron pair of a single donor atom

Question 25

Oxidation

Answer 25

The loss of electrons to form a substance. It can also be described as an increase in oxidation number.

Question 26

Oxidation number

Answer 26

The formal charge assigned to each atom in a compound according to certain rules.

Question 27

Pauli Exclusion Principle

Answer 27

An orbital holds a maximum of two electrons. No two electrons will have the same four quantum numbers.

Question 28

Quanta

Answer 28

The smallest possible discrete unit of any physical property, such as energy or matter.

Question 29

Reduction

Answer 29

The gain of electrons by a substance. It can also be described as a decrease in oxidation number.

Question 30

Spectrochemical series

Answer 30

A list of ligands in order of the size of the crystal field splitting caused in the d orbitals.

Question 31

Wavelength

Answer 31

The distance between adjacent crests or troughs of a wave.

Question 32

Wavenumber

Answer 32

The reciprocal of wavelength and has the units of cm^-1

number of cycles per cm