Chemical energetics 6.1 Energetics of a reaction Exothermic reaction: gives out energy to the surroundings. Endothermic reaction: takes in energy from the surroundings. Bond breaking is endothermic Bond making is exothermic If you subtract the energy stored in the...
-Metallic bonding: a lattice of tightly packed positive ions in a sea of electrons, resulting in crystals, therefore: Metals are malleable and ductile – the layers of ions can slide over each other Metals are good conductors – free electrons take energy...
4. Stoichiometry -In a symbol equation the number of atoms on each side of the equation should balanced for each element. -In an equation, remember to write the symbol for the state (aqueous, solid, liquid, gas) in brackets, and the oxidation state of a transition...
A mole is the Ar or Mr expressed in grams e.g. 1 mole of Carbon-12 is equal to 12 grams. It is equal to 6.02 × 1023 atoms, this number is called Avogrado’s constant. 1 mole of a gas at RTP (25°C and 1atm or room temperature and pressure) occupies a volume of 24dm3....
3.2 (b) Molecules and covalent bonds Single covalent bond: a bond where 2 non-metals share a pair of electrons to get full-outer shells as seen in H2, Cl2, H2O, CH4 and HCl represented by a line connecting the two symbols e.g. H-H Double bond is when 4 electrons are...
3.2 (c) Macromolecules Diamond: has four bonds, high melting point, does not conduct and is very hard. Used for cutting, because it is the hardest known substance (2 left pictures below). Graphite: has three bonds, made of flat sheets that are held together by...
3.2 (a) Ions and ionic bonds Ion: is a charged atom (i.e. number of protons does not equal number of electrons). They form by losing an electron (reduction) increases charge by 1, or by gaining one (oxidation) decreases charge by 1. Remember OIL RIG: oxidation is...
1.1 Bonding: the structure of matter Element: a substance that cannot be split into anything simpler, in a chemical reaction. Each element has a unique proton number. Mixture: two or more elements mixed together BUT that are not chemically combined Compound: a...
2.2 (b) Methods of purification -Filtration: Mixture goes in a funnel with filter paper, into a flask. Residue is insoluble and stays at top. Filtrate goes through. Crystallisation: Some water in the solution is evaporated so the solution becomes more concentrated....
Atoms, elements and compounds Atomic structure and the Periodic Table Particle Relative charge Mass (atomic mass units) Proton +1 1 Neutron 0 1 Electron -1 1/1840 Proton number: the number of protons in an atom (and the number of electrons in an uncharged atom)....
(a) Criteria of purity Paper chromatography: (To separate substances) a drop of the substance is placed at the centre of a piece of filter paper and allowed to dry. Three or four more drops are added to it. Water is dripped on, drip by drip, so the ink spreads...
Kinetic Theory: All substances are made of atoms, which consist of protons, electrons and neutrons. States of matter: Solid: Strong forces of attraction between particles Have a fixed pattern (lattice) Atoms vibrate but can’t change position therefore fixed volume and...
2. Experimental techniques 2.1 Measurement Variable Time Temperature Mass Volume Apparatus Stopwatch Clock Thermometer (liquid in glass, thermistor or thermocouple) Balance -beaker (a) -burette (b) -pipettes (c) -measuring cylinder (d) -gas...