| properties of solids | particles are closely packed, shape and volume do not change, vibrate in a a fixed position, they do not compress and have little kinetic energy and have strong attractive forces |
| properties of liquids | particles are slightly further apart and can slide past each other, change shape but not volume, small amount of movement and compressibility with some energy with weak forces |
| properties of gasses | particles in a gas are very far apart, change shape and volume, compress, have lots of movement and energy |
| what happens as a solid gets heated | particles gain energy and vibrate more, the forces of attraction between particles are weakened as the solid melts, |
| heating and cooling curve | heating and cooling curve |
| exothermic reaction | gives out heat |
| endothermic | absorbs heat |
| diffusion in terms of kinetic particle theory | net movement of particles from an area of higher concentration to an area of lower concentration |
| effect of relative molecular mass on the rate of diffusion of gasses | molecules that have a lower mass move faster, if light and heavy molecules have the same amount of energy when they collide the lighter ones will bounce off the heavier ones quicker, so lighter molecules will diffuse faster than heavier molecules |
| atom | the smallest particle of a chemical element that can exist, singular |
| molecule | a group of atoms bonded together |
| element | are made up of one type of atom which cannot be broken down further |
| compound | made up of 2 or more different elements chemically combined |
| mixture | two or more substances not chemically combined and can be separated by physical means, e.g. filtering |
| structure of the atom | central nucleus containing neutrons and protons surrounded by electrons in shells |
| Relative mass and charge of protons | 1, +1 |
| Relative mass and charge of neutrons | 1, no charge |
| Relative mass and charge of electrons | 0.00054, -1 |
| how to find number of protons/electrons | atomic number |
| how to find the number of protons in the nucleus | proton number/atomic number |
| how to find the total number of nucleons (protons and neutrons) in the nucleus of an atom | nucleon number/ mass number |
| how to find number of neutrons | atomic mass - number of protons |
| number of outer shell electrons | group number (downwards) |
| number of occupied electron shells | period number (across) |
| isotopes | different atoms of the same element that have the same number of protons but different numbers of neutrons |
| effect of isotopes on properties of the element | have the same chemical properties because they have the same number of electrons and therefore the same electronic configuration, but differ in mass and therefore in physical properties |
| ions | formed by the atoms gaining or losing electrons |
| cations | positively charged ions, which are formed by atoms losing electrons |
| anions | negatively charged ions, formed by atoms gaining electrons |
| ionic bond | formed when electrons are transferred between two atoms, is a strong electrostatic attraction between oppositely charged ions |
| properties of ionic compounds | high melting and boiling points, good electrical conductivity when aqueous or molten (ions are free to move to carry the current) but poor when solid (ions aren't free to move), soluble, brittle (when hit the layers slide so ions of the same charge end of next to eachother and repel) |
| why ionic bonds have these structures | a lot of heat energy is required to break this force of attraction |
| Giant ionic structures form between | metal and non-metal |
| Giant ionic structures examples | Sodium chloride |
| lattice structure of ionic compounds | lattice structure of ionic compounds |
| Simple molecule structure forms between | non-metals |
| properties of simple molecular compounds | low melting and boiling points because of weak intermolecular forces so don't require lots of energy to break, poor electrical conductivity, substances with a greater relative atomic mass have greater intermolecular forces requiring more energy to make |
| Simple molecule structure examples | oxygen |
| how is a covalent bond formed | when a pair of electrons is shared between two atoms, leading to noble gas electronic configurations |
| covalent bonds structure | if 2 electrons are shared, a single bond is formed, 4 electrons produce a double bond |
| covalent bond properties | low melting points and boiling points (require a lot of energy to break), generally do not conduct electricity except for graphite, insoluble, weak intermolecular forces between molecules |
| Giant covalent structures form between | non-metals |
| structure of graphite | structure of graphite |
| use of graphite | lubricant as an electrode |
| structure of diamond | structure of diamond |
| use of diamond | cut other diamonds in diamond tipped drill bits or saws |
| giant covalent structure of silicon oxide | each silicon atom bonded to four oxygen atoms |
| similarities between diamond and silicon dioxide | has a similar structure to diamond, so its properties are similar to diamond, it is hard and has a high melting point |
| metallic bonding | lattice of positive ions in a sea of delocalised electrons, the attraction between the positive ions and the sea of electrons forms as electrostatic charge of attractive - a metallic bond |
| metallic bonding properties | good electrical conductivity, malleable, ductile |
| molecular formula of a compound | the number and type of different atoms in one molecule |
| relative atomic mass | the average mass of the isotopes of an element compared to 1/12th of the mass of an atom of 12C |
| relative molecular mass | as the sum of the relative atomic masses relative formula mass, Mr, will be used for ionic compounds |
| empirical formula of a compound definition | the simplest whole number ratio of the different atoms or ions in a compound |
| acid | proton donors |
| strong acid | an acid that is completely dissociated in aqueous solution |
| weak acid | an acid that is partially dissociated in aqueous solution |
| acid + metal | salt + hydrogen |
| acid + metal oxide | salt + water |
| acid + metal hydroxide | salt + water |
| acid + metal carbonate | salt + water + carbon dioxide |
| acid + ammonia | ammonia salt |
| acid's effect on methyl orange | turns red immediately |
| acid + base | salt + water |
| bases | oxides or hydroxides of metals, proton acceptors |
| alkalis | soluable bases |
| bases + ammonium salts | metal salt + ammonia + water |
| alkalis effect on methyl orange | turns yellow |
| aqueous solutions of acids | H+ ions |
| aqueous solutions of alkalis | OH- ions |
| neutralization reaction (symbols) | H+ (aq) + OH- (aq) --> H2O (l) |
| how are basic oxides formed | by the direct combination of a metal with an oxygen, most metal oxides are basic oxides |
| basic oxide reactions | react with acids to form a salt and water, do not react with alkalis, most don't react with water (except group 1 and group 2 which react to form a metal hydroxide) |
| how are acidic oxides formed | direct reaction with oxygen, most non-metal oxides |
| acidic oxide reactions | react with alkalis to form a salt and water, react with water to form acidic solutions |
| amphoteric oxides | oxides that react with acids and with bases to produce a salt and water |
| 1cm to dm3 | (÷ 1000) = 0.001 |
| identifying oxygen | put a glowing splint into the test tube and if the gas is oxygen the splint will re light |
| rule for solubility | nitrates, sodium potassium and ammonium salts, sulfates EXCEPT barium calcium and lead, chlorides EXCEPT lead and silver |
| rules for insolubility | carbonates EXCEPT sodium potassium and ammonium, hydroxides EXCEPT sodium potassium ammonium and partially calcium |
| hydrated substance | chemically combined with water |
| anhydrous substance | containing no water |
| periodic table definition | an arrangement of elements in periods and groups and in order of increasing proton/atomic number |
| how can the position of an element predict its properties | each element in the group has the same number of electrons in its outer shell |
| trends in groups | group I elements get more reactive as they go down, group VII get less reactive down the group, in many groups there is a trend less metallic at the top and more metallic at the bottom |
| group I metals trends | relatively soft metals but getting softer going down, melting and boiling points decrease, low density but increase, increasing reactivity |
| group VII (halogens) trends | increasing density, decreasing reactivity, melting and boiling points increase, colour gets darker, state of halogens at room temp goes from gas to liquid to solid |
| appearance of chlorine at r.t.p | pale yellow-green gas |
| appearance of bromine at r.t.p | red-brown liquid |
| appearance of iodine at r.t.p | grey-black solid |
| transition elements | have high densities, high melting points, form coloured compounds, often act as catalysts as elements and in compounds, have ions with variable oxidation number e.g. iron (ii) & iron (iii) |
| group VIII noble gases trends and properties | all unreactive, increased boiling points, increasing density
non-metal gases, monatomic (have only one atom) |
| solvent | a substance that dissolves a solute |
| solute | substance that is dissolved in a solvent |
| solution | mixture of one or more solutes dissolved in a solvent |
| saturated solution | solution containing the maximum concentration of a solute dissolved in the solvent at a specified temp |
| residue | substance that remains after evaporation, distillation, filtration or any similar process |
| filtrate | liquid or solution that has passed through a filter |
| concentration equation | concentration = number of moles/volume of solution in dm3 |
| when is precipitation method used | if the salt you trying to make is insoluable |
| when to use titration method | bases and the salt is soluable |
| when to use insoluble base method | when the base is insoluble |
| test for ammonia | turns damn red litmus paper blue |
| test for carbon dioxide | turns limewater milky |
| test for chlorine | bleaches damp litmus paper |
| flame test for lithium | red |
| flame test for sodium | yellow |
| flame test for potassium | lilac |
| flame test for calcium | orange - red |
| flame test for barium | light green |
| flame test for copper | blue-green |
| mole | unit of amount of substance that one mole contains |
| mole calculation | moles=mass/molar mass |
| molar gas volume | 24cm3 |
| 3 common acids | hydrochloric acid, nitric acid, sulphuric acid |
| hydrochloric acid formula | HCl |
| nitric acid formula | HNO3 |
| sulphuric acid formula | H2SO4 |
| what type of acid is ethanoic acid | organic acid |
| ethanoic acid formula | CH3COOH |
| acids in water | acids produce H+ ions (aq) when dissolved in water, H+ ions are known as protons |
| taste of acids | sour |
| what salt does HCL produce | chlorides |
| what salt does H2SO4 produce | sulphates |
| what salt does HNO3 produce | nitrates |
| what salt does CH3COOH produce | ethanoates |
| what can concentration be measured in | g/dm3, mol/dm3 |
| concentration equation | concentration = moles/volume |
| dm3 to cm3 | 1 dm3=1000cm3 |
| bases | compounds that react with acids to produce a salt and water. No gases are produced in these reactions and so the only way to see the progress of any reaction is to notice any solid dissolving into the acid |
| acid reactions with litmus paper, methyl orange and thymolphthalein | turns litmus red, methyl orange red, thymolphthalein colourless |
| strong acid properties | completely dissociates in aqueous solution |
| weak acid | partially dissociates |
| HCL reaction as a strong acid | HCl (aq) → H+ (aq) + Cl-(aq) |
| ethanoic acid reaction as a weak acid | CH3COOH ⇌ H+ (aq) + CH3COO-(aq) |
| bases properties | acid opposites, feel soapy, remove the sharp taste of acids, proton accepters |
| what are alkalis | soluble bases that contain OH- ions |
| examples of alkalis | sodium hydroxide (NaOH) and ammonia (NH3) |
| neutralisation reaction formula | H+ (aq) + OH-(aq) → H2O (l) |
| when is ammonia gas released | ammonia gas is released when ammonium salts are heated with a strong base |
| test for ammonia | damp red litmus → turns blue |
| base reactions with litmus paper, methyl orange and thymolphthalein | turns litmus paper blue, methyl orange yellow thymolphthalein blue |
| indicator | a substance used to show whether a substance is acidic or basic |
| how the strength of an acid is measured | it's pH value, the more H+ (protons) that an acid gives out the lower the pH value, so acids have pH values of less than 7 |
| how the strength of a base is measured | its pH value, bases have pH values greater than 7 |
| metal oxides pH levels | metal oxides are bases, non-metal oxides are acids, some metal oxides are amphoteric e.g. aluminium oxide, and can react with an acid or a base |
| metals ions in salt | acid provides the non-metal ion for the salt, metal or base provides the metal ion for the salt |
| water of crystallisation | the water molecules present in hydrated crystals |
| valence shell | the last shell around the nucleus that electrons are found at, the electrons in the valance shell are called valence electrons |
| group I properties | called alkali metals, relatively soft, react with water with increasing reactivity down the group to form a metal hydroxide and hydrogen gas, form positively charged ions |
| group VII properties | diatomic non-metal e.g. Cl2, Br2, form negatively charged ions called halides, more reactive halogens will displace a less reactive halide |
| transition metals | high densities, form coloured compounds, high melting and boiling points, act as catalysts |
| molar gas equation | moles = vol/24 |
| metals vs non-metals | malleable and ductile as solid, brittle hard or soft
conduct heat and electricity, poor conductors
higher melting and boiling points, lower melting and boiling points |
| reactions of metals | react with oxygen or steam to form oxides, reacts with cold water a metal hydroxide is produced |
| alloy | mixture of a metal with other elements |
| what is brass made from | mixture of copper and zinc and stainless steel |
| alloys properties | can be harder and stronger than the pure metal different sized atoms in alloys mean the layers can no longer slide over each other, more useful |
| uses of alloys relating to physical properties - stainless steel | stainless steel used in cutlery due to hardness and resistance to rusting |
| structure of alloys vs metals | alloys have more things and look kinda weirder |
| uses of aluminium related to it's properties | foils and cans - easily malleable
aeroplane parts - corrosion resistance
electrical transmission lines - good electrical conductor |
| the order of reactivity | the order of reactivitiy |
| reactions of metals | reactions of metals |
| reactivity series | a measure of the tendency of a metal to form positive ions shown by its reaction with the aqueous ions or oxides of the other listed metals |
| why aluminium appears unreactive | due to the formation of a protective oxide layer on its surface, which prevents further reaction with air or water |
| what is needed for rusting of iron and steel | water and oxygen |
| methods to prevent rusting | painting, greasing and coating with plastic |
| use of zinc in galvanising as a barrier method and sacrificial protection | zinc corrodes in preference to steel and sacrifices itself to protect the steel |
| sacrificial protection | the more reactive metal has a greater tendency to lose electrons and form positive ions, hence it corrodes first |
| how barrier methods prevent rusting by excluding water or oxygen | oxygen can be excluded by storing the metal in an atmosphere of unreactive nitrogen or argon, water can be excluded by storing the metal with a desiccant |
| ease of obtaining metals | those metals placed higher up on the series (above carbon) have to be extracted using electrolysis, metals lower down on the series can be extracted by heating with carbon |
| zone 1 equation | C (s) + O2 (g) → CO2 (g), used to produce heat needed |
| zone 2 equation | CO2 (g) + C (s) → 2CO (g), reducing agent so it removes oxygen from iron oxide |
| the reduction of iron(III) oxide by carbon monoxide equation | Fe2O3 (s) + 3CO (g) → 2Fe (I) + 3CO2 (g), iron oxide is reduced to iron |
| thermal decomposition of calcium carbonate | CaCO3 (s) → CaO (s) + CO2 (g) |
| the formation of slag | CaO (s) + SiO2 (s) → CaSiO3 (casio) (l), acid-base reaction |
| main ore of aluminium | bauxite and Al is extracted by electrolysis |
| role of cryolite in extraction of aluminium | acts as a solvent for Bauxite for the extraction of Aluminium |
| physical test for water | water can be tested for by using anhydrous copper sulphate, the colour changes from white to blue |
| chemical test for water | cobalt chloride paper could be used, the colour change is from blue to pink |
| how to test for water purity | melting points and boiling points are used, water boils at 100oC and melts at 0C this is a physical test |
| why distilled water is used in practical chemistry | distilled water in used rather than tap water as it contains fewer chemical impurities |
| potential impurities from water from natural sources | dissolved oxygen, metal ions, plastics, sewage, harmful microbes, nitrates from fertilisers, phosphates from fertilisers and detergents |
| which impurities are beneficial | dissolved oxygen, metal compounds |
| potentially harmful substance | metal compounds, some plastics, sewage, nitrate & phosphates from fertilisers |
| describe water treatment | the first step is sedimentation, where water sits in tanks so mud and sand settle at the bottom. Then, it’s filtered through sand and gravel to remove smaller particles. Next, carbon filtration removes unpleasant tastes and odours. Finally, chlorine is added to kill bacteria and micro-organisms. |
| air composition | 78% nitrogen, 21% oxygen with 1% being a mixture of noble gases, water vapour and carbon dioxide |
| source of carbon monoxide pollution | incomplete combustion of carbon-containing substances |
| source of carbon dioxide pollution | incomplete combustion of carbon-containing substances |
| source of methane pollution | decomposition of vegetation and waste gases from digestion in animals |
| source of sulphur dioxide pollution | combustion of fossil fuels containing sulphur compounds |
| source of oxide pollution | of nitrogen from car engines |
| how the greenhouse gases carbon dioxide and methane cause global warming | some thermal energy is absorbed by greenhouse gases, such as carbon dioxide and methane, and is re-emitted in all directions, this reduces the thermal energy lost into space and traps it within the Earth’s atmosphere, keeping the Earth warm |
| strategies for reducing climate change | use renewable energy, using more fuel-efficient vehicle, reducing, household energy consumption, planting more trees, reduce the amount of livestock farming |
| strategies for reducing acid rain | decreasing the amount of oxides of nitrogen and sulphur dioxide that are produced, catalytic convertors in vehicles can be used to remove oxides of nitrogen |
| how nitrogen oxides form in car engines | when a car engine runs, it causes combustion by heating up quickly, this process acts as a catalyst which binds together nitrogen (N) and oxygen (O2) to form nitric oxide (NO) or nitrogen dioxide (NO2) |
| how nitrogen oxides are removed by catalytic converters | the catalysts remove the nitrogen molecule, hold onto it, and release the oxygen molecules |
| symbol equation for photosynthesis | 6CO2 + 6H2O → C6H12O6 + 6O2 |
| what are used as fertilisers | ammonium salts and nitrates |
| NPK ferterliser | contain nitrogen, potassium and phosphorus for improved plant growth, nitrogen makes chlorophyll and protein and promotes healthy leaves, potassium promotes growth and healthy fruit and flowers, phosphorus promotes healthy roots |
