AQA GCSE Chemistry Unit 3 Definitions

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  • Created by: Bryony
  • Created on: 19-05-13 21:35
1864, every 8th element had similar properties, listed in rows of 7 but this broke down by the 3rd row because of the transition elements, left no gaps for new elements
Newlands' Law of Octaves
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1869, left gaps for new elements to keep elements with similar properties in the same vertical groups, ordered by atomic mass, new elements fitted the pattern
Mendeleev's Table of Elements
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Arranged by their electronic structure, the number of the group is the number of electrons the atoms in the group have in their outer shell, more shielding = less attraction from nucleus,
The Periodic Table
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Silvery solids that are stored in oil and handled with forceps as the metals burn the skin
Alkali Metals
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More reactive with lower melting and boiling points as you go DOWN the group, form ionic compounds with non-metals, when reacted with water they produce hydrogen gas
Group 1 (Alkali Metals)
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Less reactive with higher melting and boiling points as you go DOWN the group, all exist in molecule form, form ionic bonds with metals, more reactive ones will displace less reactive ones from an aq of it's salt
Group 7 (Halogens)
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Fluorine Yellow Chlorine Green Bromine Red-Brown Iodine Grey Solid Purple Vapour
For You Can Guess But Rarely-Believe It Gets Preponderant v
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Good conductors, dense, strong, shiny, less reactive than Group 1 but are denser and have higher melting points (except mercury)
Transition Elements
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Usually have more than one ion, are colourful due to the transition metal ion they contain, all make good catalysts
Transition Metals
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Water that contains calcium and magnesium ions that limit the formation of a lather of soap, forms a scale (thermal insulator) when heated, the calcium ions are good for teeth and bones, lowers the risk of developing heart disease
Hard Water
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Water that does not contain ions
Soft Water
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Caused by the hydrocarbonate ion, can be removed by boiling or by adding sodium carbonate or by running it through ion exchange columns
Temporary Hardness in Water
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Can be softened by adding sodium carbonate or by running the water through ion exchange columns
Permanent Hardness in Water
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These contain lots of sodium or hydrogen atoms and 'exchange' them for calcium or magnesium ions in the water that runs through them
Ion Exchange Columns
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Must be free of poisonous salts and harmful microbes, from a reservoir it is screened, the solids and microbes are removed before filtration then chlorination before it reaches the house
Water
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Has nothing dissolved in it and can be made through distillation (this is expensive) and is used in chemistry labs
Distilled Water
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A reaction where the products of the reaction can themselves react to produce the original reactants
Reversible Reaction
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A reversible reaction will reach this, it means the amount of reactants and products will reach a certain point and stay there, the reactions take place at exactly the same rate in both directions so they cancel each other out
Equilibrium
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Can be moved by altering the temperature and pressure surrounding the reaction, if the temperature is raised the endothermic reaction will use the extra heat and visa versa, if the pressure is raised = less product and visa versa
Position of eqilibrium
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Industrial process that produces ammonia using nitrogen and hydrogen, it is a reversible reaction, pressure: 200 atmospheres, temp: 450C, catalyst: iron
The Haber Process
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N2(g) + 3H2 (g) <-> 2NH3 (g) (+ heat)
Reaction that takes place in the Haber Process
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Has an -OH functional group, general formula: C(n)H(2n+1)OH, Methanol, Ethanol, Propanol, used as solvents and fuels
Alcohols
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Flammable and produce carbon dioxide and water, dissolve completely in water to form neutral solutions, react with sodium to give hydrogen and alkoxides
Ethanol, Methanol, Propanol
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Have the functional group -COOH, react like other acids with carbonates -> CO2 and the salt formed in these reactions ends in -anoate, dissolve in water to produce acidic solutions
Carboxylic Acids
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Carboxylic acids with longer chains used to make soaps and detergents and also used in the preparation of esters
Carboxylic Acids in Industry
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Alcohol + Carboxylic Acid --> Ester + Water, an acid catalyst is usually used to form it, names end in -oate
Formula for Esters
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Inhaling these fumes can irritate mucus membranes in the nose and mouth, they are heavier than air and flammable, some are toxic but not as toxic as some organic solvents
Ester fumes
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6.023 x 10 to the 23
One mole
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Measured in moles per dm3, the more solute dissolved in a given volume, the more concentrated the solution
Concentration of a solution
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A type of indicatior
Phenolphthalein
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Concentration in moles x volume
Number of moles =
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Moles divided by volume
Concentration =
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Mass in grams divided by relative formula mass (Mr)
Number of moles
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Can be measured by taking the temperature of the reagents to make sure they are the same, then mixing them in a polystyrene cup and measuring the temperature at the end of the reaction
Energy Transfer
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Energy must be supplied to break bonds
Endothermic process
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Energy must be released to form bonds
Exothermic process
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Mass of water (g) x Specific heat capacity of water (4.2) x Temperature change (C)
Energy transferred (J) =
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Energy change
/_\H
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In exothermic reactions the /_\H is -ve so the line for products is lower than the line for reactants, the difference in height is energy given out in the reaction/mole, the initial rise is the activation energy, opposite is true for endothermic
Energy Level Diagrams
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Represents the minimum energy needed to break bonds between particles, lowered by catalysts
Activation Energy
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An electrical cell that's supplied with a fuel and oxygen and uses energy from the reaction to generate electricity
A fuel cell
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Lithium Crimson, Sodium Yellow, Potassium Lilac, Calcium Red, Barium Green
Little Children Sometimes Yell Pretty Loudly and Cake Regularly Beats Grapes
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Acid + Carbonate --> Salt + Water + Carbon Dioxide
Testing for CO2
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Chloride --> White precip of AgCl, Bromide --> Cream precip of AgBr, Iodide --> Yellow percip of AgI
Testing for Halide Ions
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Add dilute HCl, then barium chloride solution, if the test is positive a white precip will form
Testing for Sulphate Ions
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Other cards in this set

Card 2

Front

Mendeleev's Table of Elements

Back

1869, left gaps for new elements to keep elements with similar properties in the same vertical groups, ordered by atomic mass, new elements fitted the pattern

Card 3

Front

The Periodic Table

Back

Preview of the back of card 3

Card 4

Front

Alkali Metals

Back

Preview of the back of card 4

Card 5

Front

Group 1 (Alkali Metals)

Back

Preview of the back of card 5
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