AS – KeyWords – Flashcards
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Activation Energy |
The minimum energy that a particle needs in order to react: the energy (enthalpy) difference between the reactants and the transition state. |
Aldehyde |
An organic compound with the general formula RCHO in which there is a C=O double bond. |
Alkaline Earth Metals |
The metals in group two of the periodic table. |
Alkane |
A hydrocarbon with C-C and C-H single bonds only. With the general Formula CnH2n+2 |
Allotropes |
Pure elements which can exist in different forms in which their atoms are arranged differently. For example Diamond and Graphite are allotropes of Carbon |
Anaerobic Respiration |
The process by which energy is released and new compounds formed in living thims in the absence of oxygen. |
Atom Economy |
This describes the efficiency of a chemical reaction by comaring the total number of atoms in the product with the total number of atoms in the reactants.
Mass of Desired Product x100 =% Atom Economy Total mass of reactants |
Atom Orbital |
A region of space around an atomic nucleus where ther is a high probability of finding an electron |
Bond Dissociation Enthalpy |
The enthalpy change required to break a covalent break a covalent bond with all species in a gaseous space. |
Calorimeter |
An instrument for measureing the heat changes that accompant chemical reactions. |
Catalyst |
A substance that alters the rate of a chemical reaaction but is not used up in the reaction. |
Catalytic Cracking |
The breaking, with the aid of the catalyst, of a long chain alkane molecules (obtained from crude oil) into shorted chained hydrocarbons some of which are alkenes. |
Carbocations |
An organic ion in hich one of the carbon atoms has a positive charge. |
Carbon-neutral |
A process, or series of processes in which as much carbon dioxide is absorbed from the atmosphere as is given out. |
Chemical Feedstock |
The starting materials in an inductrial chemical reaction. |
Co-ordinate bonding |
Covalent bonding when both the electrons in the bond come from one of the atoms in the bond. (Also called dative-covalent) |
Covalent Bonding |
Describes a chemical bond between two non-metal elements, in which a pair of electrons are shared between each element. |
Cracking |
The breaking of long chain alkanes molecules into shorter chain hydrocarbons. |
Dative-Covalent Bonding |
Covalent bonding when both the electrons in the bond come from one of the atoms in the bond. (Also called Co-ordinate bonding) |
Avogadro Constant |
The total number of Particles in a mole of a substance. 6.022x1023 |
Delocalised |
Describes electrons that are spread over several atoms to help the bond together. |
Dipole-Dipole Force |
An intermolecular force that results from the attraction between molecules with permanent dipoles. |
Displacement Reaction |
A chemical reaction in which one atom or group of atoms replaces another in a compound, for example
Zn +CuO > ZnO + Cu |
Displayed Formula |
The formula of a compound drawn out so that each atom and each bond is shown. Example: |
Disproportionation |
Describes a redox reaction in which the oxidation number if some atoms of a particular element increases and that of other atoms of the same element decreases. |
Dynamic Equilibrium |
A situation in which the composition of a reaction mixture does not change because both the forward and backwards reactions are occuring at the same rate. |
Electron Density |
The probability of an electronbeing found in a particular volume or space. |
Electron Pair Repulsion Theory |
A theory which explains the shapes of simple molecules by assuming that pairs of electrons around a central atom replel each other and thus take up positions as far away from each other as possible. |
Electronegativity |
The power of an atom to attract the electrons in a covalent bond. |
Electrophile |
An electron-deficient atom, ion or molecule that takes part in an organic reaction by attacking areas of high elctron density in another reactant. |
Electrophillic Addition |
A reaction in which a C=C Double bond is saturated and in which the initial reaction is an attack by an electrophile. |
Electrostatic Forces |
The forces of attraction and repulsion between electrically charged particles. |
Elimination |
A reaction in which an atom or group of atoms is removed from a reactant. |
Empirical Formula |
The simplest whole number ratio in which the atoms in a compound combine together. |
Endothermic |
Describes a reaction in which heat is take in as the reactant change to products; the temperature of the surrounding drops. |
Enthalpy Change |
A measure of heat energy given out or taken in when a chemical or physical change occurs at constant pressure. |
Enthalpy Diagrams |
Diagrams in which the epthalpys (energies) of the reactants and products of a chemical reaction are plotted on a vertical scale to show their relative levels |
Equilibrium Mixture |
The Mixture of reactants and products formed when a reversible reaction is allowed to proceed in a close system until no further change occurs. The forward and backward reactions are still proceeding but at an equal rate. |
Exothermic |
Describes a reaction in which heat is given out as the reactant change to products; the temperature of the surrounding rises. |
Fingerprint Region |
The area of an infrared spectrum below about 1500cm-1. It is caused by complex vibrations of the whole molecule and is characteristic of a particular molecule. |
Fraction |
A mixture of hydrocarbons collected over a particular range of bp's during the fraction distillation of crude oil. |
Free Radical |
A chemical species which an unpaired electron - usually highly reactive. |
Functional Group |
An atom or group of atoms in an organic molecule which is responsable for the characteristic reaction of that molecule. |
Group |
A vertical column of elements in the periodic table. The elements have similar properties because the same outer electron arangement. |
Half Equation |
An equation for a redox reaction which considers just one of the species involved and show explicitly the electrons transferred to or from it. |
Heterogeneous Catalyst |
A catalyst which is in a different phasefrom the reactants. For example, Iron(s) in the Haber preccess Cinversion of Nitrogen(g) and hydrogen(g) to ammonia. |
Homogeneous Catalyst |
A catalyst which is in the same phase as the reactants. |
Homologeous Series |
A series which is a set of organic compounds whoch the same functional group. The compounds differ in the length of their hydrocarbon chains. |
Hydrogen Bonding |
A type of intermolecular force in whch a hydrogen atom covalently bined to an electronegative atom.
NOF!!! |
Incomplete Combustion |
A combustion reaction in which there is insufficient oxygen for all the carbon in the fuel to burn to CO2. CO and/or C (soot) are formed. |
Ionic Bonding |
Describes a chemical bond between a metal and a non-metal in which an electron or electrons are transfered from the metal to the non-metal, resulting in the formation of oppositly charges ions hich electrostatic forces of attraction between them. |
Ionisation Energy |
The energy required to remove a mole of electrons from a mole of isolated gaseous atoms or ions. |
Isomer |
One (Or more) compounds with the same molecular formula but differen structural formula. Ie : The same Atoms are arranged differently in space. |
Ketone |
An organic compound with the general formula R2CO in which there is a C=O double bond. Seconday Alcohol Oxidation. |
Lattice |
A regular 3D arrangement of atoms, ions or molecules
Eg. Macromolecular |
Leaving Group |
In an organic substitution reaction from a believing group is an atom or group of atoms that is ejected from the starting material, normally taking with it an electron pair and forming a negative ion. |
Lone Pair |
A pair of electrons in the outer shell of an atom that is not involved in bonding, also called an unshared pair. Used in a dative-covalent bond. |
Maxwel-Boltzmann Distribution |
The distribution of energies (and therfore speed) of the molecules in a gas or liquid. |
Mean Bond Enthalpy |
The average value of the bond dissociation enthalpy for a given type of bond taken froma range of different compounds. |
Metallic Bonding |
Describes a chemical bond in which out electrons are spread over a lattice of metal ions in a delocalised system.
|
Mole |
A quantity of a substance that contains the advogadro's constant (6.022x1023) of particals (eg. Atoms, molecules or Ions) |
Molecular Formula
|
A formula that tells us the numbers of atoms of each different element that makes up a molecule of a compound. |
Molecular Ion |
In mass spectrometery this a molecule of the sample which has been ionised but which has not broken up during its flight through an instrument. |
Monomer
|
A small molecule that combines with many other monomer a polymer. |
Nucleons
|
Protons and neutrons - the sub-atomic particles nuclei of atoms. |
Nucleophile
|
An ion or group of atoms with a negative charge or a partically negative - charged area that takes part in an organic reaction by attackin an electron - deficient area in another reactant. |
Neucleaphillic Substitution |
An organic reaction in whch a molecule with a partically positively charged carbon atom is attacked by a reagent with a negative charge or partially negatively charged area (an nucleophile) It results in the replacement of one of the groups or atoms from the original molecule by the nucleophile. |
Nucleus |
The tiny positively charged center of an atom composed of Protons and Neutrons. |
Oxidation |
A reaction in which an atom or group of atoms loses electrons. |
Oxidation State |
The number of electrons lost or gained by an atom in a compound compared ot the uncombined atom. It forms the basis of a way keeping track of redox (electronic transfer) reactions. Also called Oxidation number. |
Oxidising Agent |
A reagent thaat oxidises (removes electron from) another species. |
Percentage Yeild |
In a chemical reaction, this is the actual amount of product produced, divided by the theoretical yeild (predicted from the chemical equation) expressed as a %. |
Period |
A horizontal row of elements in the periodic table. There are trends in the properties as we go across the period. |
Periodicity
|
The regualr occurance of the properties of element when the are aranged in atomic number order as in the periodic table. |
Polar |
Describes a molecule in which the charge is not symetrically distributed so that one area is slightly charged and another slightly negatively charged. |
Positive Inductive Effect |
Describes the tendance of some atoms or groups of atoms to release electrons via a covalent bond. |
Proton Number |
The number of protons in the nucleus of an atom; the same as the atomic number (z) |
Redox Reaction |
Short for Reduction - Oxidation reasction, it describes reactions in which electrons are transfered from one species to another. |
Reducing Agent |
A reagent that reduces (Adds electrons too) another species. |
Reduction |
A reduction in which or group of atoms gains electrons. |
Relative Atomic Mass (Ar)
|
Ar = Adverage mass of Molecule 1/12 th mass of Carbon |