Edexcel Unit 5 Chemistry Definitions

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Oxidation
Occurs when an atom, molecule or ion loses one or more electron. The oxidation number of the element involved increases.
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Reduction
Occurs when an atom, molecule or ion gains one or more electron. The oxidation number of the element involved decreases
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Oxidising agent
A substance which oxidises another substance and is itself reduced.
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Reducing agent
A substance which reduces another substance and is itself oxidised.
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Oxidation number
The charge an atom in a compound/ion would have if it were composed only of ions.
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Disproportionation
A reaction in which an element in a single species is simultaneously oxidised and reduced.
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Standard electrode potential
The electrical potential of an electrode relative to a standard hydrogen electrode where all solutions are at 1 moldm^-3 concentration, all gases at 1 atm pressure and everything is at 298 K. It is also called the standard reduction potential.
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Standard hydrogen electrode
Its value is defined as 0V at 298 K, consisting of H gas at 1 atm passed over a platinised Pt electrode dipping into a solution of 1 moldm^-3 H+ ions at 298 K.
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Addition reaction
2 substances combine to form a single substance.
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Substitution reaction
An atom/group/compound is replaced by another atom/molecule/compound in another substance
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Elimination reaction
A simple molecule is removed from an organic molecule and is not replaced
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Electrophile
An atom/ion/group that attacks an electron-rich site and accepts a pair of electrons to dfrom a covalent bond.
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Nucleophile
An atom/ion/group that attacks a d+ atom and donates a pair of electron to form a covalent bond.
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Free radical
An atom/group with an unpaired electron - it is often very reactive or carcinogenic.
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D-block element
An element whose final electron is in a d-orbital.
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Transition metal
a metal which forms one or more stable ions with a partially-filled d-orbital.
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Ligand
a molecule/negative ion using a lone pair of electrons to form a dative covalent bond with a d-block cation.
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Coordination number
Number of atoms/ions/groups that are bonded as ligands to a d-block cation.
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Dative covalent bond
Formed when an atom donates its lone pair of electrons to another to share in a covalent bond.
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Condensation polymer
A polymer whose production also included the creation of a small molecule that is then lost.
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Addition polymer
A polymer which is formed from its entire monomers, with no loss of small molecules.
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Other cards in this set

Card 2

Front

Occurs when an atom, molecule or ion gains one or more electron. The oxidation number of the element involved decreases

Back

Reduction

Card 3

Front

A substance which oxidises another substance and is itself reduced.

Back

Preview of the back of card 3

Card 4

Front

A substance which reduces another substance and is itself oxidised.

Back

Preview of the back of card 4

Card 5

Front

The charge an atom in a compound/ion would have if it were composed only of ions.

Back

Preview of the back of card 5
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Comments

Louise

Very good resource!

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