# Chemistry OCR - Atoms, Bonds and Groups

Unit 1 - Module 1

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• Created by: Denise24
• Created on: 04-03-14 16:44
Isotopes
atoms of the same element with different numbers of neutrons
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Atomic (proton) number
the number of protons in the nucleus of an atom
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MAss (nucleon) number
the number of particles (protons and neutrons) in the nucleus
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Ion
a positively or negatively charged atom or (covalently bonded) group of atoms
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Relative isotopic mass
the mass of an atom of an isotop compared with 1/12 of the mass of an atom of carbon-12
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Relative atomic mass
the weighted mean mass of an atom of an element compared with 1/12 of the mass of an atom of carbon-12
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Relative molecular mass
the weighted mean mass of a molecule compared with 1/12 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 1/12 of the mass of an atom of carbon-12
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Amount of a substance
the quantity whose unit is the mole
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the number of atoms per mole of the carbon-12 isotope (6.02 x 10^23 per mol)
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Mole
the amount of any susbstance containing as many particles as there are carbon atoms in exactly 12g of the carbon-12 isotope
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Molar mass
the mass per mole of a substance. The units of molar mass are g/mol
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Empirical formula
the simplest whole-number ratio of atoms of each element present in a compound
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Molecule
a small group of atoms held together by covalent bonds
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Molecular mass
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. At room temperature and pressure, the molar mass is 24.0 dm^3/mol
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Concentration
of a solution is the amount of solute, in mol, dissolved per 1 dm^3 (1000 cm^3) of solution
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Standard solution
a solution of known concentration. Standard solutions are normally used in titrations to determine unknown information about another susbstance
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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 substances taking part in a reaction
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Acid
a species that is a proton donor
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Base
a species that is a proton acceptor
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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 any acid when a H+ ion fromthe acid has been replaced by a metal ion or another positive ion, such as the ammonium ion
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Cation
a positively charged ion
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Anion
a negatively charge ion
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Hydrated
refers to a crystalline compound containing water molecules
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Anhydrous
refers to a substance that contains no water molecules
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Oxidation number
a measure of the number of electrons that an atom uses to bond with atoms of another element. Oxidation numbers are derived from a set of rules.
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Oxidation
loss of electrons or an increase in oxidation number
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Reduction
a gain of electrons or a decrease in oxidation number
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Redox reaction
a reaction in which both reduction and oxidation take place
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Reducing agent
a reagent that reduces (adds electron to) another species
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Oxidising agent
a reagent that oxidises (takes electrons from) another species
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## Other cards in this set

### Card 2

#### Front

the number of protons in the nucleus of an atom

#### Back

Atomic (proton) number

### Card 3

#### Front

the number of particles (protons and neutrons) in the nucleus

### Card 4

#### Front

a positively or negatively charged atom or (covalently bonded) group of atoms

### Card 5

#### Front

the mass of an atom of an isotop compared with 1/12 of the mass of an atom of carbon-12