Unit 1 definitions

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Atomic Number
The number of protons in the nucleus of an atom.
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Mass Number
The number of particles (protons and neutrons) in the nucleus of an atom.
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Isotopes
Atoms of the same element with different numbers of neutrons and therefore different masses.
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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 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 Molecular Mass, Mr
The weighted mean mass of a molecule compared with one-twelfth of the mass of an atom of carbon-12.
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Relative Formula Mass
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
The amount of any substance containing as many particles as there are carbon atoms in exactly 12g of the carbon-12 isotope.
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Avogadro's Constant, NA
The number of particles per mole (6.02x10^23)
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Molar Mass
The mass per mole of a substance. The units of molar mass are gmol-1.
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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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Acid
A proton donor. An acid releases H+ ions in aqueous solution.
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Base
A proton acceptor.
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Alkali
A soluble base that releases OH- ions in aqueous solution.
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Salt
Any chemical compound formed from an acid when a H+ ion from the acid is replaced by a metal ion or other positive ion (such as the ammonium ion, NH4+).
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Hydrated
Refers to a crystalline compound which contains water molecules.
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Anhydrous
Refers to a substance that contains no water molecules.
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Water of Crystallisation
Refers to water molecules that form an essential part of the crystalline structure of a compound.
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Oxidation
The loss of electrons and an increase in oxidation number.
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Reduction
The gain of electrons and a decrease in oxidation number.
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Reducing Agent
A reagent that loses electrons in order to reduce another species.
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Oxidising Agent
A reagent that gains electrons in order to oxidise another species.
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First Ionisation Energy
The energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions.
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Successive Ionisation Energy
The energy required to remove each electron in turn.
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Ionic Bond
The electrostatic attraction between oppositely charged ions.
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Covalent Bond
A shared pair of electrons.
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Dative Covalent Bond (Coordinate Bond)
A shared pair of electrons where both the electrons that are shared are from one of the bonding atoms only.
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Electronegativity
The ability of an atom to attract the shared pair of electrons in a covalent bond.
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Metallic Bonding
The electrostatic attraction between positive metal ions and delocalised electrons.
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Other cards in this set

Card 2

Front

The number of particles (protons and neutrons) in the nucleus of an atom.

Back

Mass Number

Card 3

Front

Atoms of the same element with different numbers of neutrons and therefore different masses.

Back

Preview of the back of card 3

Card 4

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 4

Card 5

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 5
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