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31 Cards in this Set
- Front
- Back
Mass number
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Mass number = number of protons + neutrons (in the nucleus/atom)
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Relative atomic mass
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Average/mean mass of an atom divided by 1/12 the mass of an atom of 12C
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First ionisation energy
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The energy required to remove 1 (mole) electron(s) from 1 (mole) gaseous atom(s), forming 1 (mole) ion(s) with a single positive charge.
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Dynamic equilibrium
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Rate of forward reaction = rate of backward reaction (1) concentrations of reactants and products remain constant. (1)
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Empirical formula
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A formula which gives the simplest whole number ratio of atoms of each element in a compound.
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Covalent bond
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A shared pair of electrons.
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Co-ordinate (dative) bond
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A covalent bond in which the shared pair of electrons are provided by just one of the bonded atoms.
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Electronegativity
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The power of an atom to attract electrons towards itself in a covalent bond.
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Atomic radius
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The distance from the centre of the nucleus to the outer electrons of an atom.
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Structural isomerism
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Compound which have the same molecular formula but different structures/different structural formulae/different displayed formulae.
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Homologous Series |
A family of organic molecules which all contain the same functional group, but have an increasing number of carbon atoms. |
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Activation Energy |
Minimum energy (1) to start a reaction (1) |
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Catalyst |
Speeds up a reaction but is chemically unchanged at the end (1) |
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Stereoisomers |
Compounds with the same structural formula (1) but a different arrangement of atoms in space (1) |
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Hess' Law |
Enthalpy change is independent of the route taken |
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Nucleophile |
Electron pair donor. |
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Enthalpy Change |
Change in heat energy under a constant pressure. |
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Standard Enthalpy Change of Formation |
The enthalpy change when one mole of a substance is formed from its constituent elements under standard conditions, with all reactants and products in their standard states. |
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Standard Enthalpy Change of Combustion |
The enthalpy change when one mole of a substance is completely burned in Oxygen under standard conditions, with all reactants and products in their standard states. |
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Bond Enthalpy |
Enthalpy change to break one mole of covalent bonds in the gaseous state. |
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Mean Bond Enthalpy |
Enthalpy change to break one mole of covalent bonds in the gas phase average over a range of compounds. |
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Polymerisation |
The joining together of monomers (1) to form long chains (1) |
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Reduction/Oxidation |
Reduction = gain, Oxidation = loss |
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Reducing/Oxidising Agents |
RA = electron donors, OA = electron acceptors |
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Rate of Reaction |
The change in concentration of a substance in unit time. |
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Le Chatelier’s principle |
If a system in equilibrium is disturbed, equilibrium will shift to oppose that change. |
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Disproportination |
A reaction in which the same species is simultaneously oxidised and reduced. |
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Avogadro's Constant |
Number of particles present in a mole (6.02 x 1023 mol-1). |
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Percentage Atom Economy % |
mass of desired product (Mr)/ total mass of reactants x 100 - include coefficients. |
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Electrophile |
An electron-deficient atom/ion. |
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Free Radical |
A chemical species with an unpaired electron. |