AS UNIT 1 Chemistry Definitions

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Isotopes
Atoms with the same number of protons but different number of neutrons
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Atomic number (Z)
The number of protons in the nucleus. All atoms of the same element have the same number of protons.
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Mass number (A)
The total number of protons and neutrons in the nucleus of an atom of an element
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Relative atomic mass (Ar)
The weighted mean mass of an atom of an element compared with one-twelfth of the mass of an atom of carbon-12
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Relative isotopic mass
The mass of an atom of an isotope compared with one-twelfth of the mass of an atom of carbon-12.
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Relative molecular mass (Mr)
The weighted mean mass of a formula unit compared with one-twelfth of the mass of an atom of carbon-12.
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Mole (mol)
The amount of any substance containing as many particles as there are carbon atoms inexactly 12g of the carbon-12 isotope.
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Molar mass (M)
The mass per mole of a substance. The units of molar mass are g mol^-1
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Avogadro constant
The number of atoms per mole of the carbon-12 isotope: (6.02 x 10^23)
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Concentration
The amount of solute, in mol, dissolved per 1 dm^3 (1000 cm^3) of solution.
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Empirical formula
The simplest whole number ratio of atoms of each element present in a compound.
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Molecular formula
The actual number of atoms of each element in a molecule.
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Molar volume
The volume per mole of a gas. The units of molar volume are dm^3 mol^-1. At room temperature and pressure, the molar volume is approximately 24.0 dm^3 mol^-1
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Standard Solution
A solution of known concentration
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Species
Any type of particle that takes part in a chemical reaction
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Stoichiometry
The molar relationship between the relative quantities of a substances taking part in a reaction
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Acid
A species that produces H+ ions from an aqueous solution. They are proton acceptors
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Base
A species that removes H+ ions from an aqueous solution. The are proton donors
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Alkali
A type of base that dissolves in water forming hydroxide ions, OH- (aq) ions.
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Salt
Any chemical compound formed from an acid when a H+ ion from the acid has been replaces by a metal ion or another positive ion
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Hydrated
A crystalline compound containing water molecules
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Anhydrous
A substance that contains no water molecules.
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Water of crystallisation
Water molecules that form an essential part of the crystalline structure of a compound
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Oxidation
The loss of electrons
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Reduction
The gain of electrons
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Oxidation number
The measure of the number of electrons that an atom uses to bond with atoms of another element
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Redox reaction
A reaction in which both reduction and oxidation take place
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Oxidising agent
A reagent that oxidises (takes electrons) from another species
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Reducing agent
A reagent that reduces (adds electrons to) another species
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Other cards in this set

Card 2

Front

The number of protons in the nucleus. All atoms of the same element have the same number of protons.

Back

Atomic number (Z)

Card 3

Front

The total number of protons and neutrons in the nucleus of an atom of an element

Back

Preview of the back of card 3

Card 4

Front

The weighted mean mass of an atom of an element compared with one-twelfth of the mass of an atom of carbon-12

Back

Preview of the back of card 4

Card 5

Front

The mass of an atom of an isotope compared with one-twelfth of the mass of an atom of carbon-12.

Back

Preview of the back of card 5
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