Chemistry definitions

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  • Created by: Ikra Amin
  • Created on: 09-10-13 11:12
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 atmoic 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 compared with one twelfth of the mass of an atom of carbon-12
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Mole
The number of particles per mole - 6.02x10(to the power of 23)
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Avogadro's constant, Na
The number of particles per mole - 6.02x10(to the power of 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 released H+ ions in aqueous solution
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Base
A proton acceptor
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Alkali
A soluble base that released OH- ions in aqeous solution
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Salt
Any chemical compound formed from an acid when a H+ ion from the acid has been replaced by a metal ion or other positive ion, such as the ammonium ion, NH4+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 that contains no 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
Is the loss of electrons or an increase in oxidation number
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Reduction
Is the gain of electrons or a decrease in oxidation number
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Reducing agent
Is 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
An electrostatic attraction between two oppositley charged ions
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Covalent bond
A shared pair of electrons
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Dative covalent (co ordinate bond)
A shared pair of electrons where both electrons that are shared are from the one of the bonding atoms only
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Electronegativity
The ability of an atom to attract the bonding 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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