chem eoy

• an atom is the smallest part of an element that can exist
• an element is a substance made up of only one type of atom
• coloumns = groups, rows= periods
• an atom has an overall charge of 0
• dalton discovered that atoms are tiny hard spheres that cannot be broken down.
• thomson discovered the plum pudding model. atoms are general balls of positive charge and there are scattered electrons.
• rutherford discovered the nuclear model. he fired alpha particles at a thin sheet of gold. some absorbed and some deflected. after bohr he discovered protons.
• bohr discovered electron shells orbiting the atom (nucleus) and prevents it from collapsing
• chadwick discovered neutrons within the nucleus.
• todays atom we look at is mostly bohr’s model.
• isotopes are atoms of the same element with the same number of protons and electrons but different mass number due to difference in neutron.
• electronic configuration 


  first shell: 2 electrons

  second shell: 8 electrons

  third shell: 8 electrons
• the number of occupied shells is equal to the period number
• an ion is a charged particle formed when one or more electron are lost or gained from an atom or molecule
• john newlands arranged the properties into groups of 8 - known as the law of octaves
• dmitri mendeleev arranged elements in order of increasing relative atomic mass. he left gaps in his table for elements to be discovered.
• chemists didn’t agree to the periodic table because metals and non-metals were in the same group. some boxes had two elements. mendeleev reversed the order of some elements
• melting point decreases as you go down group 1.
• group 1 elements are all solids at room temp.
• group 1 elements are called alkali metals because they produce an alkaline solution when reacted with water.
• group 7 elements are called halogens
• group 7 elements have low melting and boiling points and are poor conductors of heat and electricity
• as you go down group 7, melting and boiling points increase
• transition metals can be used as catalysts in certain reaction.
• insoluble 


  a solid which is unable to dissolve
• solvent


  a liquid which can have a solid dissolved into it
• saturated


  a solution in which no more solute can dissolve
• solution


  a liquid with a solid dissolved into it
• soluble 


  anything which is able to dissolve
• solute


  the solid which is dissolved into a liquid
• an acid releases H+ ions in aqueous solutions and neutralise base
• a base is a substance that neutralises an acid
• an alkali is a soluble hydroxide that releases OH- ions in aqueous solutions.
• metal + acid -> salt + hydrogen
• metal oxide + acid -> salt + water
• metal hydroxide + acid -> salt + water
• metal carbonate + acid -> salt + water + carbon dioxide
• displacement reactions


  a more reactive metal can displace a less reactive metal from a compound
• unreactive metals such as gold are found in earths crust as combined as elements
• phytomining uses plants to absorb copper compounds. plants are harvested and then burned to produce ash that contains the copper compounds.