Unit 1-Glossary Flashcards
Electromagnetic radiation
can be described in terms of waves and characterised in terms of wavelength and/or frequency.
Electromagnetic spectrum
Radiowave-microwaves-infrared-visible-ultraviolet-xrays-gamma rays
Wavelength
The length of a complete wave (e.g. measured from one crest to another).
Frequency
The number of waves passing a fixed point per second. Given the unit of Hertz (Hz)
Velocity
The speed at which a wave advances
Wavenumber
The number of waves in a given distance (e.g. per metre or per centimetre)
Photons
A particle or packet on energy carried as part of the electromagnetic spectrum (often as visible light).
Quanta
The smallest “packet” of energy that can exist
Excited state
The position of electrons in an atom after it has absorbed a photon of energy, promoting electrons to higher energy levels.
Ground state
The position of electrons in an atom under normal conditions
Atomic absorption/emission spectroscopy
An analytical technique which measures the intensity of light being absorbed/emitted by a sample. This is proportional to the concentration of the sample.
Orbital
A region of space which can hold a maximum of two electrons.
Heisenberg’s uncertainty principle
It is impossible to know the exact position and velocity of an electron at any given time. We can only define areas of probability of finding an electron called an orbital.
Pauli exclusion principle
Electrons occupying the same orbital must have opposite spins.
Aufbau principle
Lower energy orbitals are filled before higher energy orbitals.
Degenerate
Of equal energy
Hund’s rule of maximum multiplictity
Electrons occupy all degenerate orbitals singly, with their spins in the same direction, before pairing up (and reversing their spin).
Spectroscopic/orbital box notation
A method of fully describing the arrangement of electrons in an atom.
Oxidation
An increase in oxidation number in a reaction
Reduction
A decrease in oxidation number in a reaction
Transition metal
a metal which has an incomplete d subshell in one of it ions.
Complex
A central metal ion surrounded by ligand.
Ligand
electron donors which may be negative ions or molecules with non-bonding pairs of electrons
Monodentate ligand
negative ions or molecules which donate one non-bonding pair of electrons to a central metal ion
Bidentate ligand
Negative ions or molecules which donate two non-bonding pairs of electrons to a central metal ion
Polydentate ligand
negative ions or molecules which donate more that one non-bonding pair of electrons to a central metal ion.
Co-ordinate bond
A bond where the shared electrons are provided by one atom
Spectrochemical series
A list of ligands arranged in order of the extent of d-splitting (Δ) that the ligand causes
Entropy
a measure of the degree of disorder (or chaos) in a system.
Standard entropy
a measure of the degree of disorder (or chaos) in a system.
Free energy
the part of the total energy of a system that can do work at constant temperature and pressure completely.
