OCR Definitions: Atoms, Bonds & Groups

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  • Created by: Loomy
  • Created on: 12-12-13 12:22
Relative atomic mass (Ar)
The weighted mean/average mass of an atom of an element compared to 1/12th of the mass of an atom of carbon-12
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Relative isotopic mass
The mass of an atom of an isotope compared to 1/12th of the mass of an atom of carbon-12
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Relative molecular mass (Mr)
The weighted mean/average mass of a molecule compared to 1/12th of the mass of an atom of carbon-12
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Relative formula mass (giant structures)
The weighted mean/average mass of a formula unit compared to 1/12th of the mass of an atom of carbon-12
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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 number of atoms of each element in a molecule
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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 protons plus neutrons in the nucleus of an atom
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Isotopes
Atoms of the same element with different masses. The isotopes of an element have the same number of protons (and electrons), but different numbers of neutrons
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Acid
Releases H+ ions in aqueous solutions
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Base
Readily accepts H+ ions from an acid
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Alkali
Soluble base that releases OH- ions in water
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Oxidation
The loss of electrons; an increase in oxidation number
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Reduction
The gain of electrons; a decrease in oxidation number
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Disproportionation
The oxidation and reduction of the same element in a redox reaction
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First ionisation energy
The energy required to remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions
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Second ionisation energy
The energy required to remove 1 electron from each 1+ ion in 1 mole of gaseous 1+ ions to form 1 mole of gaseous 2+ ions
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nth ionisation energy
The energy required to remove 1 electron from each (n-1)+ ion in 1 mole of gaseous (n-1)+ ions to form 1 mole of gaseous n+ ions
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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
A shared pair of electrons with only one of the atoms contributing both electrons
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Electron pair repulsion theory
Electron pairs repel each other and the number (and type) of electron pairs around the central atom determines the shape of a covalent molecule
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Electronegativity
A measure of the attraction of a bonded atom for the pair of electrons in a covalent bond
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Polar bond
A covalent bond between two atoms with different electronegativities in which the bonded electron pair of one is drawn closer to the more electronegative atom
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Polar molecule
A molecule in which the electron density is not equally distributed, resulting in areas of high electron density (δ+) and areas of low electron density (δ-)
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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 mass of an atom of an isotope compared to 1/12th of the mass of an atom of carbon-12

Back

Relative isotopic mass

Card 3

Front

The weighted mean/average mass of a molecule compared to 1/12th of the mass of an atom of carbon-12

Back

Preview of the back of card 3

Card 4

Front

The weighted mean/average mass of a formula unit compared to 1/12th of the mass of an atom of carbon-12

Back

Preview of the back of card 4

Card 5

Front

The simplest whole-number ratio of atoms of each element present in a compound

Back

Preview of the back of card 5
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