Chemistry Knowledge Triple 1 PDF

The smallest part of an Have a radius of around 0.1 Before the discovery of the Atom...

The smallest part of an Have a radius of around 0.1 Before the discovery of the Atom Tiny solid spheres that electron, John Dalton said the element that can exist nanometres and have no charge (0). Pre 1900 could not be divided solid sphere made up the different elements and Around 100 different elements each elements. compounds Contains only one type of Element one is represented by a symbol e.g. O, Atoms, atom JJ Thompson ‘s experiments Na, Br. 1897 A ball of positive charge showed that showed that an atom ‘plum with negative electrons Two or more elements Compounds can only be separated must contain small negative Compound pudding’ embedded in it chemically combined into elements by chemical reactions. charges (discovery of electrons). - Ernest Rutherford's alpha particle 1909 - - Positively charge nucleus Central nucleus Contains protons and neutrons - + scattering experiment showed nuclear - at the centre surrounded - - that the mass was concentrated at model - negative electrons Electron shells Contains electrons the centre of the atom. Niels Bohr proposed that electrons Electronic Max number of 1913 Electrons orbited in fixed shells; this was shell electrons Bohr orbit the nucleus at supported by experimental structures Name of Relative Relative Electronic model specific distances Particle Charge Mass 1 2 observations. Proton +1 1 2 8 The development of James Provided the evidence to Neutron 0 1 3 8 the model of the atom Chadwick show the existence of neutrons within the nucleus Electron -1 Very small 4 2 A beam of alpha particles are Rutherford's scattering AQA GCSE directed at a very thin gold foil Most of the alpha particles Relative electrical charges of subatomic particles passed right through. Atomic structure experiment - A few (+) alpha particles were and periodic - - deflected by the positive Mass The sum of the protons and neutrons in the 7 number nucleus table part 1 - + - nucleus. A tiny number of particles Li Atomic The number of Number of electrons = - reflected back from the 3 number protons in the atom number of protons - nucleus. Two or more elements or compounds Can be separated by Show chemical reactions - need Law of conservation of mass states Mixtures Chemical not chemically combined together physical processes. reactant(s) and product(s) energy the total mass of products = the equations always involves and energy change total mass of reactants. Method Description Example Uses words to show reaction Does not show what is Separating an insoluble solid To get sand from a mixture of Word Filtration equations reactants  products happening to the atoms or the from a liquid sand, salt and water. number of atoms. magnesium + oxygen  magnesium oxide To separate a solid from a To obtain pure crystals of sodium Crystallisation Uses symbols to show reaction Shows the number of atoms and solution chloride from salt water. Symbol equations reactants  products molecules in the reaction, these To separate a solvent from a 2Mg + O2  2MgO need to be balanced. Simple distillation To get pure water from salt water. solution 35Cl (75%) and 37Cl (25%) atomic mass Fractional Separating a mixture of liquids To separate the different Atoms of the same element Relative distillation each with different boiling points compounds in crude oil. with the same number of Relative abundance = Separating substances that move Isotopes (% isotope 1 x mass isotope 1) + (% isotope To separate out the dyes in food protons and different Chromatography at different rates through a numbers of neutrons 2 x mass isotope 2) ÷ 100 colouring. e.g. (25 x 37) + (75x 35) ÷ 100 = 35.5 medium –