Pregunta | Respuesta |
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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