AQA GCSE Chemistry

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 ...

Mixture A combination of two or more substances that are not chemically joined. Filtration Separates insoluble solids from liquids. Crystallisation The formation of crystals by cooling a saturated solution Simple distillation Used to separate a liquid from a solution

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...

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

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

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

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

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

Atom Smallest part of an element Element A pure substance made of only one kind of atom Compound A substance made up of atoms of two or more different elements joined by chemical bonds Mixture A combination of two or more different substances that are not joined by chemical bonds

First shell can hold 2 electrons 2nd and 3rd shell can hold 8 electrons no of shells = Period on the periodic table Valence electrons Outer shell electrons which are involved in reactions No of valence electrons = Group number on the periodic table Hydrogen electron structure 1 Nitrogen ...

Ancient greek model of the atom Atoms are tiny solid spheres which cannot be divided. JJ Thompson Discovered the electron and developed the "plum-pudding" model of the atom plum pudding model of the atom atoms are balls of positively charge with negative electrons embedded in it

Relative mass of a proton 1 Relative mass of a neutron about the same as that of a proton Relative mass of an electron 1/1840 Relative charge of a proton +1 Relative charge of a neutron 0 Relative charge of an electron -1 Neutral atoms same number of positive protons as negative electro...

What is the charge of a proton? - +1 What is the charge of a neutron? - 0 What is the charge of an electron? - -1 What is the relative mass of a proton? - 1 What is the relative mass of a neutron? - 1 What is the relative mass of an electron? - Very small How many types of atoms do elements co...