Classtie

Tough supporting wall of the eye - Sclera Transparent outer layer found at the front of the eye. Refracts (bends) light into the eye - Cornea Contains muscles that allow it to control the diameter of the Pupil (hole in the middle) and therefore how much light enters the eye - Iris Focuses light onto the retina - Lens Contains receptor cells sensitive to light intensity and colour - Retina Controls the shape of the lens - Ciliary Muscles and Suspensory Ligaments Carries impulses from the r...

Natural Hazard - A natural hazard is a natural process which could cause death, injury or disruption to humans, or destroy proprty or posesions. Natural disaster - A natural hzard that has actualy happened Geological hazards - Caused by kand and tectonic processes Meteorological hazards - Caused by weather and climate Factors affecting hazard risk - Urbanisation, poverty, development, climate change Tectonic plates - Slabs of the Earth's crust Continental crust - thicker and less dense ...

Name of Group 7 elements The halogens Group 7 elements have similar chemical properties because they all have 7 outer shell electrons Diatomic molecule A molecule consisting of two atoms Chemical structure of group 7 diatomic molecules Pattern in melting points and boiling points down group 7 melting and boiling points decrease Pattern of reactivity down the halogens they get less reactive Reason for patterns in reactivity larger atomic radius, more shielding, less nuclear attractio...

Formation of metal ions Atoms lose outer electrons Metals Elements that form positive ions Formation of non-metal ions Atoms gain electrons Charge on non-metal ions negative Group 1 ions charge +1 Group 2 ions charge +2 Group 6 ions charge -2 Group 7 ions charge

Metals Elements which form positive ions Non-metals Elements which do not form positive ions Metals position on periodic table on the left hand side Non-metals position on periodic table

Metal An element that forms positive ions pH of metal oxide Basic Non-metal Does not form positive ions pH of non-metal oxide Acidic Reduction in terms of oxygen Loss of oxygen Oxidation in terms of oxygen Gain of oxygen Oxidation in terms of electrons Loss of electrons

H - Hydrogen He - Helium Fe - Iron N - Nitrogen Na - Sodium F - Fluorine Li - Lithium C - Carbon CO2 - carbon dioxide O - Oxygen Mg - Magnesium

Requirements for a reaction to take place Particles must collide, with sufficient energy Activation energy Minimum amount of energy required to start a chemical reaction Reaction profile diagram A graph which shows the change in energy of a chemical reaction Products The new substances formed by a chemical change

Mixture A combination of two or more substances that are not chemically joined. Filtration Separates insoluble solids from liquids. Crystallisation

Transition elements are found In the middle block of the periodic tableRe Physical properties of transition elements Hard, high melthing points, strong and dense. Chemical properties of transition elements Slow/no reaction with oxygen, water and halogens Charges on transition metal ions Form positive ions often with the ability to form more than one ion