# chemistry as level unit 1

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• Created by: Anna Wood
• Created on: 10-01-15 16:19
Ionisation energy
Energy required to remove an electron from each atom of a one mole of gaseous atoms to create one mole of gaseous ions.
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Empirical formula
The lowest whole number ration of each element present in a compound
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Molecular formula
The actual number of atoms of each element present in a compound
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Electron shielding
The repulsion of electrons in different inner shells, shielding reduces the net attraction force from the positive nucleus on the outer shell electron.
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The region in which an atom can hold two electrons with opposite spins
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Ion
A positively or negative charged atom or (covalently bonded) group of atoms ( a molecular ion)
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Isotopes
Are atoms of the same element with a different number of neutrons but the same electron and proton number.
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Atomic number
The number of protons in the nucleus of an atom.
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Mass number
Number of protons and neutrons in the nucleus of an atom.
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Relative isotopic number
The mass of an atom of an isotope compared to 1/12 of the mass of carbon 12.
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Relative molecular mass
Weighed mean mass of an molecule compared to 1/12 the mass of an atom of carbon 12.
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Relative formula mass
The weighed mean mass of a formula unit compared with 1/12 of the mass of an atom of carbon 12.
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Amount of substance
Is the quantity who units is the mole. Chemist use the amount of substance as a means of counting atoms
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The number of atoms per a mole of carbon 12 = 6.02x10 23 mol-1
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Mole
Is the amount of any substance containing the amount of particles as there are carbon atoms in exactly 12g of carbon 12.
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Molar mass
Mass per a mole of substance units= g mol-1
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Molecule
A small group of atoms held together by covalent bonds.
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Molecular formula
Actual number of atoms of each element in a molecule.
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Molar volume
The volume per a mole of a gas units = dm3 mol-1 . at room temperature and pressure = 24dm3
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Concentration of a solution
Amount of solute , in mol, dissolved per 1dm3.
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Standard solution
A solution of known concentration. Normally used in titrations to determine unknown information about other substances .
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Stoichiometry
Molar relationship between the relative quantities of substances taking part in a reaction.
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Acid
A proton donor .
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Base
Proton accepter.
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Salt
Any chemical compound formed from an acid when H+ ions from the acid has been replaced by a metal ion or another positive ion such as ammonium.
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Cation
Positively charged ion.
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Anion
Negatively charged ion.
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Hydrated
Refers to a crystalline compound containing water molecules.
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Anhydrous
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 number
Measure of the number of electrons that an atoms used to bond with an atoms of another element, oxidation numbers are derived from a set of rules.
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Redox reaction
Reaction in which both reduction and oxidation takes place.
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Oxidation
A loss of electrons or an increase in oxidation numbers.
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## Other cards in this set

### Card 2

#### Front

The lowest whole number ration of each element present in a compound

#### Back

Empirical formula

### Card 3

#### Front

The actual number of atoms of each element present in a compound

### Card 4

#### Front

The repulsion of electrons in different inner shells, shielding reduces the net attraction force from the positive nucleus on the outer shell electron.

### Card 5

#### Front

The region in which an atom can hold two electrons with opposite spins

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