Unit 1 Definitions Flashcards
Electronegativity definition
Electronegativity is a measure of the attraction an atom involved in a bond has for the electrons of the bond.
Frequency definition
Frequency is the number of wavelengths that pass a fix point in one unit of time
Absorption spectrum
A spectrum consisting of dark absorption lines superimposed on a bright continuous spectrum; it shows absorption of radiation by a material over a range of wavelengths
Aufbua principal
States that orbitals are filled in order of increasing energy
Bidentate
A ligand that contains two atoms with lone pairs of electrons capable of bonding to a metal atom or ion
Complex
A complex consists of a central metal atom or ion surrounded by Ligands
Dative/coordinate bond
A covalent bonds in which one of the atoms supplies both of the electrons of the shared pair
Coordination compounds
Compounds in which a central metal atom or ion is attached to a group of surrounding molecules or ions by dative covalent bonds (also known as coordinate bonds)
Coordination number
The coordination number is the total number of dative covalent bonds to the metal atom or ion.
It is not the number of ligands attached
Dative covalent bond
In this type of covalent bonds, both the shared electrons originally came from the same atom
Degenerate
A set of atomic orbitals that are of equal energy to each other
Electromagnetic spectrum
This is the range of frequencies or wavelengths of electromagnetic radiation
Emission spectroscopy
The study of emission spectra produced by excited substances (often gaseous atoms or molecules)
Excitation energy
The minimum energy required to change a system from its ground state to a particular excited state
Ground state
This is the lowest possible electronic configuration electrons in an atom can adopt
Heisenberg’s uncertainty principle
This principle states that it is impossible to state precisely the position and the momentum of an electron at the same instant
Hexadentate
A ligand that bonds to a metal ion using electron pairs on six donor atoms
Hund’s rule
When degenerate orbitals are available, electrons fill each singly, keeping the spins parallel, before pairing starts.
Ionisation
The addition or removal of an electron to create an ion
Ionisation energy
Ionisation energy is the energy required to remove one mole of electrons from one mole of atoms in the gaseous state
Ligands
Molecules or ions that bond to the central metal atom or ion in a complex
Lone pair
A lone or non-bonding pair of electrons is a pair of outer or valence shell electrons (that have opposing spins) which are not used to form covalent bonds within the molecule
Molecular orbital
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 atomic orbitals
Monodentate
A ligand that bonds to a metal atom or ion using the electron pair of a single donor atom
Oxidation
Oxidation is the loss of electrons from a substance. It can also be described as an increase in oxidation number.
Oxidation number
The formal charge assigned to each atom in a compound according to certain rules
Pauli exclusion principle
This states that an orbital hold a maximum of two electrons
Quanta
The smallest possible discreet unit of any physical property, such as energy or matter.
Reduction
Reduction is the gain of electrons by a substance. It can also be described as a decrease in oxidation number
Spectrochemical series
A list of ligands in order of the size of the crystal field splitting caused in the d-orbitals
Wavelength
The distance between adjacent crests or troughs of a wave
Wave number
Wave number is the reciprocal of wavelength and has the units of cm-1
Energy associated with a single photon formula
E = hf
Energy associated with one mole of photons
E = Lhc/y
How can EM radiation be described
EM radiation can be described as a wave and as a particle and is said to have a dual nature
What happens when a photon is absorbed or admitted
Electrons within the substance of gain or lose energy
Repulsion strength of lone and bonding pairs
Repulsion between non-bonded pairs (lone pairs) is greater that that between bonding pairs of electrons.
Bond angles of tetrahedral, pyramidal, angular
Tetrahedral: 109.5
Pyramidal: 107
Angular: 104.5
Transition metal definition
A transition metal is defined as a metal that, in at least one of its stable ions, has a partially filled d subshell
Oxidation number of free or unconvinced elements
Zero
What is the oxidation number in most compounds for hydrogen and oxygen
Hydrogen = +1
Oxygen = -2
Notable exceptions:
Metallic hydrides: -1 for hydrogen
Peroxides: -1 for oxygen
In compounds what oxidation number does fluorine always have
-1
In a molecule, what must the oxidation numbers equal
The algebraic sum of all the oxidation numbers in a molecule must be equal to 0
What must the oxidation numbers in a polyatomic ion be equal to
The algebraic sum of all the oxidation numbers in a polyatomic ion must be equal to the charge on ion
Naming complexes - neutral ligands exceptions
H20 becomes aqua or aquo
NH3 becomes ammine
CO becomes carbonyl
Rest of neutral ligands are given their normal names
Latin name for iron
Ferrate
Latin name for copper
Cuprate
Latin name for tin
Stannate
Latin name for silver
Argentate
Latin name for lead
Plumbate
