Chemistry Unit 2 definitions

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  • Created by: ava.scott
  • Created on: 13-04-14 12:52
Empirical Formula
The simplest whole number ratio of atoms of each element in a molecule.
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Molecular Formula
The actual number of atoms of each element in a molecule.
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General Formula
The simplest algebraic formula of a member of a homologous series.
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Homologous series
Series of organic compounds that have the same fucntional group, similar chemical properties, but change by 1 carbon and 2 hydrogen atoms as you go up the group.
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Structural isomers
Compounds with the same molecular formula but different arrangement of atoms.
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Stereoisomers
Compunds with the same structural formula but a different arrangement in space e.g. E/Z isomers
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Homolytic fission
When a covalent bond is broken, and gives an electron to both atoms, to make two free radicals.
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Heterolytic fission
When a covalent bond is broken and both bonded electrons go to one atom, forming a cation and an anion.
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Radical
A species with one unbonded/unpaired electron
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Nucleophile
An electron pair donor
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Electrophile
A electron pair reciever/acceptor
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Addition reaction
A reaction in which a reactant is added to turn a unsaturated molecule to a saturated one (no double bonds)
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Substitution reaction
A reaction in which an atom/group of atoms are replaced by another atom/group of atoms.
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Elimination reaction
when a atom is removed from a saturated molecule to make an unsaturated molecule.
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Atom economy
The Molecular mass of useful products produced divided by the molecular mass of unuseful products produce, x100
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Percentage Yield
The actual mass of desired product divided by the maximum mass of desired product x 100
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Hydrocarbon
A molecule that contains just atoms of elements carbon and hydrogen.
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Sigma Bond (σ bond)
A bond formed directly from the head on overlap of two atoms.
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Pi Bond (π bond)
A bond formed above and below the plane of an atom by the sideways over lap of p-orbitals
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Polymer
A chain made up from repeating units called monomers.
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Monomers
A small molecule that combines with other monomers to make a polymer.
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Activation Energy
The minimum energy required to begin a reaction by breaking bonds.
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Standard conditions
Room temp- 298K and 100kpa (or 1atm)
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Enthalpy
The heat content that is stored in a chemical system
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Exothermic Reaction
A reaction in which the products have less energy than the reactants.
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Endothermic reaction
A reaction in which the products have more energy than the reactants.
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Standard enthalpy change of reaction ΔHrΘ
The enthalpy change that accompanies the molar quantities as stated in a chemical equation, with all reactants and products being in their standard states.
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Enthalpy change of formation
The enthalpy change when one mole of a product is formed from its constituent elements, with all reactants and products in their standard state.
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Enthalpy change of combustion
The enthalpy change when one mole of a reactant is completely burnt with oxygen, to form the combustion products, with all reactants and products in their standard state.
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Average bond enthalpy
The average enthalpy change when breaking by homolytic fission one mole of a bond in the molecule of a gaseous species.
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Hess's law
That the enthalpy change of reaction is independent of the route take
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Heat Capacity
The energy require to raise the temperature of 1g of a substance by 1 degree Celsius.
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Catalyst
Increases the rate of reaction without be consumed by the overall reaction.
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Heterogeneous catalysis
The catalyst is in a different state to the reactants.
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Homogeneous catalysis
The catalyst is in the same state as the reactants.
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Dynamic equilibrium
The quilibrium that exists in a closed system when the rate of the forward reaction is equal to the rate of the reverse reaction.
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le Chatelier's principle
When a system in dynamic equilibrium is subjected to change the position of the equilibrium will shift to minimise the change.
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Other cards in this set

Card 2

Front

The actual number of atoms of each element in a molecule.

Back

Molecular Formula

Card 3

Front

The simplest algebraic formula of a member of a homologous series.

Back

Preview of the back of card 3

Card 4

Front

Series of organic compounds that have the same fucntional group, similar chemical properties, but change by 1 carbon and 2 hydrogen atoms as you go up the group.

Back

Preview of the back of card 4

Card 5

Front

Compounds with the same molecular formula but different arrangement of atoms.

Back

Preview of the back of card 5
View more cards

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