Chemistry definitions F321

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  • Created by: I.m
  • Created on: 11-12-12 21:51
Isotope
Isotopes are atoms of an element with the same number of protons but different number of neutrons.
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Relative isotopic mass
The mass of an atom of an isotope of an element relative to 1/12th 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 relative to 1/12th of the mass of an atom of carbon-12.
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Relative molecular mass Mr
The mass of a molecule of a compound relative to 1/12th of the mass of an atom of carbon-12.
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Relative formula mass
The relative formula mass of a compound is equal to the sum of the individual relative atomic masses.
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Mole
1 mole is the amount of substance which contains as many particles as there are atoms in exactly 12g of carbon-12.
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Empirical formula
The simplest whole number ratio of atoms of each element in a compound.
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Molecular formula
The actual number of atoms of each element in a molecule.
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Concentration
Concentrations are expressed as the number of moles of solute present in 1dm3 of solution.
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Standard solution
A solution of a known concentration.
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Concentrated solution
Solutions containing a higher number of moles of solute in a given volume of solution are described as concentrated.
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Dilute solution
Solutions containing a fewer number of moles of solute in a given volume of solution are described as dilute
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Hydrated
Salt containing water molecules known as water of crystallisation.
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Anhydrous
A substance that contains no water of crystallisation.
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Acid
An acid is a proton, H+, donor.
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Base
A base is a proton, H+, acceptor.
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Salt
A salt is formed when the acidic H+ ion of an acid is replaced by a positive ion such as a metal ion or the ammonium ion.
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Oxidation
Loss of electrons (or an increase in oxidation number).
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Reduction
Gain of electrons (or a decrease in oxidation number).
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First ionisation energy
The first ionisation energy of an element is the energy required to remove one electron from each atom in 1 mole of gaseous atoms to form one mole of gaseous 1+ ions.
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Second ionisation energy
The energy required to remove one electron from each ion in 1 mole of gaseous 1+ ions to form 1 mole of gaseous 2+ ions.
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Salt
A salt is formed when the acidic H+ ion of an acid is replaced by a positive metal ion such as a metal ion or the ammonium ion.
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Shell
A group of atomic orbitals with the same prinicpal quantum number, n. Also known as a main energy level.
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Sub-shell
A group of the same type of atomic orbitals (s, p, d, f) within a shell.
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Atomic orbital
A region within an atom that can hold up to two electrons with opposite spins.
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Ionic bonding
The electrostatic force of attraction between oppositely charged ions.
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Covalent bond
A covalent bond is formed when atoms share a pair of electrons, one electron being contributed by each atom.
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Dative covalent bond
A dative covalent bond is when atoms share a pair of electrons which has been provided by one of the bonding atoms only.
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Lone pair
An outer shell pair of electrons that is not invovled in chemical bonding.
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Electronegativity
Electronegativity is the ability of an atom to attract the electron pair(s) in a covalent bond.
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Intermolecular force
An attractive force between neighbouring molecules. Intermolecular forces can be Van der Waals' forces (induced dipole-dipole forces), permanant dipole-dipolen forces or hydrogen bonds.
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Van der Waals' forces
Very weak attractive forces between induced dipoles in neighbouring molecules.
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Hydorgen bond
A strong dipole-dipole attraction between an electron-defiient hydrogen atom (O-δ+ or N-Hδ+) on one molecule and a lone pair of electrons on a highly electronegative atom (H-O:δ+ or H-N:δ-) on a different molecule.
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Metallic bonding
The electrostatic attraction between positive metal ions and delocalised electrons.
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Periodicity
The trend in properties that is repeated across a period.
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Dispropornation
The oxisation and reduction of the same element in a redox reaction
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Other cards in this set

Card 2

Front

The mass of an atom of an isotope of an element relative to 1/12th of the mass of an atom of carbon-12.

Back

Relative isotopic mass

Card 3

Front

The weighted mean mass of an atom of an element relative to 1/12th of the mass of an atom of carbon-12.

Back

Preview of the back of card 3

Card 4

Front

The mass of a molecule of a compound relative to 1/12th of the mass of an atom of carbon-12.

Back

Preview of the back of card 4

Card 5

Front

The relative formula mass of a compound is equal to the sum of the individual relative atomic masses.

Back

Preview of the back of card 5
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