IGCSE Chemistry

• sulphur is an impurity that can be present in fuels. sulphur reacts combusts with oxygen to form sulphur dioxide. this pollutes the air and can cause acid rain.
• phenolphthalein is colourless in acids and is pink in alkalis
• flourine is a colourless gas
• chlorine is a pale green gas, it bleaches litmus paper
• bromine is an orange liquid and is used to test for alkenes
• iodine is a purple solid
• an element is one type of atom
• a compound is two or more atoms chemically bonded together
• a mixture is two or more different atoms not chemically bonded together
• diffusion is the movement of a substance from high concentration to low concentration
• simple distillation is separating two solutions based on different boiling points
• filtering is separating a insoluble solid from a liquid
• fractional distillation is separating a mixture of liquids
• isotopes have the same number of protons and different number of neutrons. they have the same chemical properties as the number of outer shell electrons are the same. they have different physical properties due to the molecular mass of the atom
• elements in the same group have the same number of outer shell electrons so they react in the same way
• elements in the same period have the same number of shells
• noble gases are unreactive as they have a full outer shell
• allotropes of giant covalent bonds are graphite and diamond
• Solution- The mixture formed when a solute is dissolved in a solvent
• copper gives a blue precipitate of Cu(OH)2 in testing for copper ions
• Iron gives a green precipitate of Fe(OH)2 in testing
• iron gives a brown precipitate of Fe(OH)3 in testing
• oxygen relights a glowing splint
• flourine is a pale yellow gas
• chlorine is a pale green gas which bleaches litmus paper
• bromine is a brown liquid used for testing alkenes
• iodine is a purple solid
• water turns anhydrous copper sulphate blue
• pure water boils at 100C and freezes at 0C
• carbon dioxide turns limewater cloudy
• carbon monoxide is a product of incomplete combustion
• copper carbonate is green and decomposes to CuO (black) upon heating
• copper oxide is black
• magnesium oxide is white
• oxygen is hazardous when stored as a gas as it can cause an explosion due to high pressure
• when sulphur burns in oxygen a blue flame is present
• atoms have no overall charge as they contain the same number of protons and electrons
• isotopes react in the same way as the have the same number of electrons
• copper powder turns black when copper oxide forms
• gas shrinks when cooled