The atmosphere.pdf

2.1 Planet Earth as a source of chemicals major of the chemicals atmosphere source 地殼 Earth's crust :...

2.1 Planet Earth as a source of chemicals major of the chemicals atmosphere source 地殼 Earth's crust : , ocean , and noble nitrogen , oxygen gas sodium chloride & chloride magesium 電解 ↳ electrolysis of sea can produce chlorine, hydrogen and sodium hydroxide metal coal , , petroleum , natural gas 2.2 Classification of matter Pure substances & mixture Matter-anything that occupies space & has mass ↳ be classified into substance & mixtures pure can substances which haven't Mixture = two or more pure chemically combined together Air is not a pure substance mixture of carbon dioxide) ↳ gases (nitrogen oxygen , , , pure substance Elements & compounds Elements = pure substance that can't be broken down into simpler substances by chemical methods substance Sif contains impurities / dissolved substances Ce minerals/salts mixture pure. g. Water (H , O) be broken down into hydrogen (H2l & oxygen it can COS by passing electricity through X element electricity water , hydrogen + oxygen can't be broken down into simpler substances - ~elements Mass of elements in the Earth's crust Calcium 3 6% Oxygen : 46 6 %. :. Silicon : 27 7 %. Sodium : 2 8%. Aluminium : 8 1 %. Potassium : 2 6. % Iron : 5 % Magnesium : 2 1 %. All other elements : 1 5. % Compounds pure substance made up of two or more elements chemically together sodium chlorine ↳ e water carbon dioxide common salt (sodium chloride). g. , , , sugar sodium chloride can be produced by burning a piece of sodium metal (silver solid) in chlorine (yellow-green) gas Mixtures & compounds iron iron (II) + sulphur < sulphide Mixture - Compound Composition by mass variable (can be mixed together in any proportion) fixed Chydrogen & oxygen by mass is always 1: 8 in water formation Changes in no chemical reaction (heat) has chemical reaction (heat absorbed/given out Melting point (m p ).. & a range of temperature (X sharp m. p /b p. ).. a sharp temperature (v sharp m. p & b p.. ). boiling point (b. p. General properties retains its different from its constinent elements own properties many are Separation of constituents methods chemical methods physical  Matter-anything that occupies space & has mass I I Mixturee, separation by physical methods > Pure substance X air direct mixing impure substance ↳ mixture of gases (nitrogen oxygen , , carbon dioxide paration by chemical methods Compounds chemical combination Elements broken down into simpler = pure substance made up of two or more = pure substance that can't be elements chemically together substances by chemical methods