Chemistry Definitions AS

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Flashcards on Chemistry Definitions AS, created by wg.fox on 01/04/2014.
wg.fox
Flashcards by wg.fox, updated more than 1 year ago
wg.fox
Created by wg.fox over 10 years ago
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Question Answer
Definitions As Definitions for As Chemistry
UNIT 1 ......
Amount Structure ......
Atomic Number Number of protons in the nucleus of an atom
Mass Number Total number of the protons and neutrons in the nucleus of one atom of an element
1st Ionisation Energy Is the energy required to remove one mole of electrons from one mole of gaseous atoms
2nd Ionsation energy The energy required to remove one mole of electrons from one mole gaseous +1ions
Amount of substance ....
Relative atom mass The average mass of an atom of an element compared to one-twelfth of the mass of an atom of carbon-12
Relative molecular mass The mass of one molecule of the compound relative to one-twelfth of the mass of an atom
Mole The amount of substance in grams that contains as many particles (atoms, molecules, ions, electrons) as there are atoms in 12 g of carbon 12
Avogadro Constant Is the number of particles in one mole of any substance. It is equal to 6.023x10 23
Molar Mass The mass of one mole of an element or a compound
Molarity The concentration of a solution with units of mol dm-3
Empirical Formula The simplest whole number ratio of atoms of each element in a compound
Molecular Formula The actual number of atoms of each element in a compound
Bonding .....
Ionic Bonding Electrostatic force of attraction between two oppositely charged ions in a lattice. Ions are formed by electron transfer
Covalent Bonding Atoms bound by a shared pair of electrons
Co-ordinate Bonding Dative covalent bonding where the shared pair of electrons in a covalent bond is donated by a single atom
Metallic bonding electrostatic forces of attraction between cations in a lattice and the de-localised electrons between them
Dipole-Dipole The intermolecular forces between two polar molecules
Van Der Waals (Induced Dipole-Dipole or London forces) The intermolecular forces between non-polar molecules e.g. Cl-Cl
Hydrogen Bonding The intermolecular bonding between Hydrogen and either Oxygen, Fluorine or Nitrogen through the electrostatic attraction between the unshielded hydrogen proton and the lone pair on each of O, F or N
Electronegativity The relative attraction atoms have for the shared pair of electrons in a covalent bond
Intro to Organic Chem ......
Functional Group Is an atom or group of atoms that gives the organic compound its characteristic chemical properties
Homologous Series A series of compounds of similar structure in which each member differs from the next by a common repeating unit, CH2
Positional Isomerism The molecular formula and functional group are the same, but the position of the functional group is different
Chain Isomerism The molecular formula and functional group are the same, but the arrangement of the carbon atoms is different
Functional Group Isomerism The molecular formula is the same, but the functional group is different
Chain Isomerism (Branch chain isomers) The molecular formula is the same, but the hydrocarbon chain is arranged differently
Structural Isomerism The same molecular but the structural formula is different
Alkanes ....
Saturated Hydrocarbon A hydrocarbon that contains single bonds only
Unsaturated Hydrocarbon A hydrocarbon that contains at least one carbon-carbon double bond
UNIT 2 ......
Energetics ........
Hess' Law If a reaction may occur by more than one route the energy change is the same regardless of the route taken
Mean Bond Enthalpy The energy required to break one mole of covalent bonds between two given atoms averaged across a range of compounds
Kinetics ............
Activation Energy Activation energy is the minimum energy required for a reaction to occur
Catalyst A catalyst is a substance that speeds up a chemical reaction but is itself unchanged at the end of the reaction
First Law of Thermodynamics Energy can be neither created nor destroyed but it can be converted from one form to another
Standard Enthalpy Changes Standard enthalpy changes refer to energy changes under conditions of constant pressure
The standard enthalpy of formation The standard enthalpy of formation is the enthalpy change when 1 mole of a compound is formed from its elements in their standard states under standard conditions
Standard enthalpy of combustion The enthalpy change when 1 mole of a substance is completely burned in oxygen under standard conditions
Standard enthalpy of neutralisation The enthalpy change when 1 mole of water is formed when an acid neutralises an alkali under standard conditions
Equilibra .........
Le Chatelier's Principle The equilibrium position will shift to oppose any change in conditions
Dynamic Equilibrium Equilibrium where the reaction is: continuous in both directions, same rate when the reaction is both forward and backwards and has relative concentrations of reactants and products that remain constant
Redox ..........
Oxidation State The hypothetical charge on an atom in a species when that species, irrespective of the nature of bonding, is regarded as totally ionic
Oxidising Agent Electron Acceptors
Reducing Agents Electron Donors
Oxidation Oxidation is loss of electrons
Reduction Is the gain of electrons
Halogens ........
Disproportionation A reaction in which a species becomes both oxidised and reduced
Haloalkanes ....................
Homolytic Fission The electrons from a covalent bond are shared when the bond breaks
Free radical A reactive intermediate which results from homolytic fission
Nucleophile A species that can donate a lone pair of electrons on bond formation
Electrophile An electron deficient species which accepts a pair of electrons on bond formation
Alkenes ..............
Positional Isomerism The molecular formula are the same, but the position of the double bond is different
Stereoisomerism The same molecular and structural formula, but a different orientation in space
Geometric Isomers The two stereoisomers have the structural formula but the bonds are arranged differently in space
Carbocation A very reactive intermediate with a positive change on a carbon atom
Alcohols ................
Biofuel A fuel derived or produced from renewable biological sources
Analytical Techniques ......................
Molecular ion An ion formed in mass spectrometer which is the result of ionisation, but not fragmentation of the molecule
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