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Elements of life.

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Terminology (Including Scientific International Units) Atom: Smallest whole particle, can not be broken down in a chemical reaction Molecule: Two or more atoms covalently bonded Balanced Equation: Same number of each atom on each side, since in a closed system, according to the Law of Conservation of Mass, the total mass is the same after a chemical reaction as before, equations must balance Empirical formula: Simplest ratio of types of atoms in substance e.g. CH2(ethene.) In an equation, oxygen is calculated by the difference. Molecular formula: Actual numbers of different types of atom e.g. C2H4 (ethene) Structural formula: Shows how the atoms are arranged H-O-H 1 dm3 = 1 litre = 1000cm3 10ml = 1cl Moles 1 mol: Quantity of particles ( Avagadro constant (L) = no. atoms in 12g of Carbon12 isotope 1 mol = 6.023 x 1023 mol-1 ) 1 mol dm -3 = 1 mole of substance in something else e.g. 1M HCl in Water Relative Atomic Mass (also RAM or Ar) The amount of substance which has 1mol of particles there will be 6.023 x 1023 mol-1 particles. The Carbon 12 isotope is used to compare the masses to because the actual masses are far too small to be used. It is calculated by: Relative atomic mass Ar = Average mass of an atom of an element x 12 Mass of one atom of Carbon 12 Average mass is used because there are isotopes Moles = Mass RAM Relative Molecular Mass (also RMM or Mr) The sum of Ars in a molecular substance Relative molecular mass Mr = Average mass of an atom of an entity x 12 Mass of one atom of Carbon 12 Entity means simplest formula unit e.g. H20 Moles = Mass RMM This is very similar to formula mass, and the same principles apply, however, molecular mass applies only to covalent substances, in ionic compounds the formula unit is not a molecule, but is a group of ions. ...read more.


H H H H H H + n According to the Big Bang theory, all elements in our bodies originate from nuclear fusion reactions. At the high temperatures in gas clouds of stars the electrons have enough energy to escape the nuclei, so the gases are ionised, in a plasma, in which the positive ionised electrons are in a 'sea' of delocalised negative electrons. They have very different properties to the same gases at lower temperatures. Plasma forms the stars and so is the most common form of matter in the universe. It is hoped that nuclear fusion reactions can be harnessed to produce electrical energy on earth, but safely generating the temperatures required for plasma and containing it sustainably, safely and economically, is very difficult. Mass spectrometers Inside a mass spectrometer there is a vacuum. There is also an ionisation chamber, into which a sample of the vapour of an element is injected, and then bombarded with electrons, the collisions with them cause the atoms to lose an electron and form positive ions. This beam is accelerated by an electric field, then deflected by a magnetic field. The amount of deflection varies according to the charge to mass ratio of the ions. Since the charge is the same for all electrons, the deflection varies according to the mass. Lighter ions, from lighter isotopes are more deflected than heavier ones, so different mass particles can be separated and identified. The detector counts the number of each different ion forming upon it and so a percentage of the abundancy of each isotope can be measured. X (g) + e- X+ (g) + 2e- Light Wave model - Light is a form of electromagnetic radiation with wavelength and frequency, it always travels the same distance in the same medium in the same time, in c, e.g. c= 3 x 108 ms-1 in a vacuum. Wavelength (?) ...read more.


Then enough sulphuric acid should be added to dissolve all the solid, using a glass rod to stir it. Then use a funnel to transfer the beaker contents into a 250cm3 volumetric flask, using sulphuric acid to ensure it is all transferred. Then dilute sulphuric acid should be added until it is about 1cm below the graduation mark. The beaker should then be stoppered and inverted to mix the solution. Some should then be added to the burette. Just one extra drop of MnO4- in this case, would turn the solution purple Spectroscopy - how light and matter interact Clean the end of a Nichrome wire (not the end with the cork on!) by heating it strongly and then dipping into concentrated Hydrochloric Acid, repeat this until when in the flame, the colour does not change. Then clamp a spectroscope horizontally inline with the Bunsen flame. Moisten the tip of the wire with distilled water, and dip it into a metal chloride and look through the spectroscope at the colour of the flame. Chemistry of Group 1 and 2 elements 1. Observations of reactions of them with water can be made, and then pH measured with universal indicator 2. Heating them in a test tube and then bubbling the gas through limewater can be done to see the thermal stability of the carbonates of them Lab procedure * Before using equipment it should be cleaned with distilled water * The meniscus should just touch the graduation marker when measuring * A pipette should be used to add the last 1 cm of a substance so that it is accurate * The burette should be run out initially to remove any air bubbles, into a spare beaker * The tap should be turned with one hand, gradually, and the other hand should stir the beaker * The volume on the buttette should be recorded before and after the titration * The first attempt should be approximate to give an idea for the others * It should then be repeated until the three volumes are within 0.1cm3 of each other ...read more.

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