Module 2 - Keywords Flashcards
Isotopes
Atoms of the same element with different numbers of neutrons and different masses
Relative Isotopic Mass
Mass of an isotope compared to 1/12th of the mass of carbon-12
Relative Atomic Mass
Weighted mean mass of an atom compared with 1/12th of the mass of carbon-12
Relative Molecular Mass, Mr
Mass of a molecule compared with 1/12th of the mass of carbon-12
Mole
- The unit for an amount of substance (6.02 x 10^23 particles)
- The amount of substance containing as many particles as there are carbon atoms in exactly 12g of the carbon-12 isotope
Avogadro Constant
The number of particles per mole, (6.02 x 10^23 mol^-1)
Molar Mass
Mass per mole, g mol^-1
Mass Spectrometry
Method used to determine the relative abundances of different isotopes
Empirical Formula
Simplest whole number ratio of atoms of each element present in a compound
Molecular Formula
Number and type of atoms of each element in a molecule
Anhydrous
Contains no water
Hydrated
Contains water of crystallisation
Ideal Gas Equation
pV=nRT
Stoichiometric Relationships
The whole number relationships between the particles of reactants and products
Percentage Yield
actual yield / expected yield x 100
Atom Economy
useful products / total product x 100
Acid
Proton donor, release H+ ions in aqueous solution
Base
Proton acceptor
Alkali
A soluble base that releases OH- ions in aqueous solution
Neutralisation
A reaction of H+ + OH- –> H2O
Titration
The slow addition of one solution ok a known concentration to a known volume of another solution of unknown concentration until the end point
Strong Acid
An acid that completely dissociates in water HA –> H+ + A-
Weak Acid
An Acid that only partially dissociates in water HA H+ + A-
Dilute Acid
An acid with only a few particles dissolved per litre (e.g. 0.01 mol dm^-3)
Concentrated Acid
An acid with lots of particles dissolved per litre (e.g. 50.01 mol dm^-3)
Oxidation Number
A measure of the number of electrons involved in bonding. Used to work out what has been oxidised/reduced
Oxidation
- Loss of electrons
- Increase in oxidation number
- Adding oxygen
Reduction
- Gain of electrons
- Decrease in oxidation number
- Removing oxygen
Redox
A reaction in which one substance is oxidised and another reduced
Salt
The compound formed when the hydrogen in an acid is replaced by a metal
Orbital
A region around the nucleus that can hold up to two electrons, with opposite spins
Subshell
Orbitals which have the equivalent energy levels. S subshell contains 1 orbital, p subshell contains 3 orbitals, d subshell contains 5 orbitals
Electron Configuration
Shows how many electrons are arranged in the subshells. e.g. oxygen: 1s22s22p4
Ionic Bond
Electrostatic forces of attraction between positive and negative ions
Giant Ionic Lattices
Structure resulting from oppositely charged ions in all directions e.g. NaCl
Covalent Bond
A shared pair of electrons
Dative Covalent Bond
A shared pair of electrons where both electrons originate from the same atom
Average Bond Enthalpy
A measurement of covalent bond strength. It is the energy change associated with breaking 1 mol of bonds in gaseous molecules
Electron Pair Repulsion Theory
The idea that electron pairs repel and so affect the shape of the particles. Non bonded pairs repel more than bonded pairs
Linear
Shape caused by having 2 bonded pairs and 0 non-bonding electron pairs - which repel as far as possible. The bond angle is 180º
Non-linear
Shape caused by having 2 bonding and one or two non-bonding electron pairs which repel as far as possible . The bond angle will be 118º or 104.5º
Trigonal Planar
Shape caused by having 3 bonding and 0 non bonding electron pairs which repel as far as possible. The bond angle will be 120º
Pyramidal
Shape caused by having 3 bonding and 1 non bonding electron pairs which repel as far as possible. The non bonding pairs repel more than bonding pairs. The bond angle will be 107º
Tetrahedral
Shape caused by having 4 bonding and 0 non bonding electron pairs which repel as far as possible. The bond angle will be 109.5º
Octahedral
Shape caused by having 6 bonding and 0 non bonding electron pairs which repel as far as possible. The bond angle will be 90º
Electronegativity
The ability of an atom to attract the bonding electron in a covalent bond
Polar Bond
A covalent bond in which there is a permanent dipole due to differing electronegativities of the bonded atoms
Dipole
Having a positive and a negative end
Induced Dipole
An instantaneous dipole caused by dipoles on neighbouring molecules
London forces
Induced dipole-dipole interactions between molecules
Hydrogen Bond
Intermolecular bonding between molecules containing N, O or F and the H atom of -NH, -OH or -HF
