• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Chemistry GCSE Definitions

Extracts from this document...


UNIT 1 - Structure and Bonding Atomic structure Proton - +1 Electron - weighs 1/1836 -1 Neutron - changes for isotopes (neutral) Isotopes do not change the atomic number, but increase the mass number because of the increase in neutrons, This will change the relative atomic mass depending on spread of isotopes. Mass spectrometry, sample in gaseous state vaporised, and bombarded with electrons, forming positive ions which are accelerated and passed by a magnet which then splits apart different strengths, forming a graph showing abundance of different species. Can find isotopes Relative atomic mass can be calculated First ionisation energy The amount of energy required to remove one mole of electrons from each atom in the gas phase to form a singly positive ion. Second ionisation energy The amount of energy required to remove the next electron from an atom. Requires more energy after the first, since this will usually lead to open electrons, or electrons left in unfilled shells. Jump to between shells requires a lot more energy, and shows large peak on graph Across periodic table generally increases but then drops when starting a new row because, outer shell contains one electron an so is not held well due to nuclear shielding *Slight dips occur at between elements which have half filled shells, since the next element ...read more.


Lattice enthalpy is the energy change per mole for the process M+ + X- = MX Ignores polarisation so actual covalence can be calculated Covalence increases lattice energy P/S orbs head on lap for sigma bonds P orbs side lap for pi bond A covalent bond is polar if there is a large difference in electronegativity Electronegativity is the measure of how strongly an atom attracts electrons when in a covalent bond. Two bonded pairs - linear 180 Two bonded two lone - bent linear 104 Three bonded pairs - trigonal planer 120 Three bonded, one lone pair - pyramidal 107 Three bonded, two lone pairs - t shaped two 90 and one 180 Four bonded pairs tetrahedral - 109.5 Five bonded pairs - trigonal bipyramid 3 are 120 and two 90 Six bonded pairs - octahedron 90 Two double bonds linear 180 One double, two single - trigonal planer 120 Two double bonds, two single - tetrahedral 109.5 Two double bonds, one lone pair - bent linear 104 Noble gases increase in temperature for mpt *Hydrides also Group 7 Fluorine pale yellow gas Chlorine greenish gas Bromine brown volatile liquid Iodine dark grey lustrous solid The hydrogen halides are very soluble Produce strong acids HF has strongest bond, and decreases down the group Have high ionisation energies Produce ppts with Ag+ ions, of which chloride is soluble with NH3, bromide with conc. ...read more.


the pressure and physical states of the reactants and products are the same in each case Enthalpy of dissociation energy - enthalpy change when mole of a gaseous substance is broken up into free gaseous atoms Can also be called and enthalpy for covalent bonds Organic Carbon can catenate, form bonds with itself homologous series - similar chemical properties, gradual variation, formula Nucleophiles - species which seek out positive centres and must have a lone pair if electrons to donate to form a covalent bond Electrophiles - species which seek out negative centres and must be capable of accepting a lone pair of electrons to form a covalent bond Aliphatic - normal aromatic - contain rings do not obey rules Free radical (can form from breaking bonds like Cl2) homolytic fission Calculating energy per unit - moles gives g; divide kj by moles to get kgperg then times by density for calorific value (kjcm-3) A tertiary iodide will be the most reactive because the C-I bond is the weakest and is on the third carbon. Alcohols CnH2n+1OH Aldehydes and keytones - CnH2nO (keytone cant have H as second R group) CnH2n+1CO2H (INSERT SYNTHETIC PATHWAY SUMMARY) Kinetics Kinetic stability means that the reactants are thermodynamically unstable but do not have enough energy to react to react and so are kinetically stable. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Classifying Materials section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Classifying Materials essays

  1. Marked by a teacher

    Identifying an Ionic Compound. Objectives: To learn and test for metal ions ...

    5 star(s)

    Repeat for K+, Ca2+, Cu2+ Procedure - Part 2: Testing for an unknown Ionically Bonded Substance: 0. Choose individually a test tube with an unknown ionically bonded substance. 0. Get 5 empty test tubes and divide equally the unknown ionically bonded substance in each of the 5 test tubes.

  2. The rates of reaction between CaCO3 and HCL

    The two samples are plotted on the same graph so same axis and the curve for the west data is steeper and higher. This shows that the speed of the reaction was higher but also that more C02 was produced.

  1. Affect of concentration on reaction

    1st Mass Loss (g) 2nd Mass Loss (g) Average Mass Loss (g) 0 0.0000 0.0000 0.0000 5 0.2480 0.2590 0.2535 10 0.2650 0.2710 0.2680 15 0.2730 0.2800 0.2765 20 0.2810 0.2890 0.2850 25 0.2880 0.2970 0.2925 30 0.2950 0.3040 0.2995 35 0.3010 0.3110 0.3060 40 0.3060 0.3170 0.3115 45 0.3110

  2. The role of mass customization and postponement in global logistics

    In response many major companies are considering their options, taking a long hard look at the supply chains in which they participate and questioning whether activities are appropriately positioned in terms of time and location. The key to mass customizing effectively is called postponement.

  1. chemistry open book:formation of natural and synthetic rubber

    The accelerators used in curing contain at least one sulphur atom, this helps kick start the reaction between the rubber and sulphur. Improvements in rubber due to additives Rubber is not make off 100% rubber it contains additives which improve its qualities Rubbers 55% Carbon black 26% Oils 7% Resins

  2. To conjecture the structure and bonding of eight unknown solids by analysis of experimentally ...

    charged particles free to move * Shatters/crumbles but with less defined fractures - it breaks up without fracturing - Not entirely rigid internal structure * Lowest (66?C) melting point - Weak intermolecular bonds "D" is soluble only in non-polar solvents and is not conductive.

  1. An experiment to investigate the factors that determine the amount of energy released when ...

    This is because the total bond enthalpies in the alcohol and oxygen molecules are larger than the bond enthalpies in the carbon dioxide and the water molecules. It also means that it gives out heat when burned. This is displayed in the sketch graph on the right.

  2. Investigation on the combustion of Alcohols.

    quickly cover the flame so that no more mass is burnt off and leave the lid on so that there isn't any evaporation. Then read the temperature of water and note down the highest temperature the thermometer records. Then weigh the end mass of the alcohol and note it down,

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work