questions

• mass number


  the sum of the number of neutrons and protons in an atomic nucleus
• atomic number


  the number of protons in an atom
• Relative atomic mass


  relative atomic mass = sum of (isotope abundance × isotope mass number) ÷ sum of abundance of all the isotopes
• Isotopes


  Different atomic forms of the same element

  
  

  same atomic number BUT different mass numbers
• Compounds


  formed from two or more elements held together by chemical bonds

  
  

  formed from sharing and taking electrons
• ionic bonding


  metal + nonmetal
• covalent bond


  nonmetal + nonmetal e.g carbon monoxide
• Filtration


  A process that separates insoluble solids from liquids.
• Evaporation


  The change of a substance from a liquid to a gas

  
  

  the solvent will evaporate and the solution will become more concentrated. Eventually crystals will start to form
• Crystallisation


  The formation of crystals (as solvent evaporates from solution)
• rock salt practical


  crush it up

  mix it with water

  FILTER it

  EVAPORATE

  leave it to crystallise
• Distillation


  Separation of a liquid from a solution by evaporating and condensing
• Fractional distillation


  Method to separate a liquid mixture by using their different boiling points
• John Dalton


  Created the atomic theory
• JJ Thomson


  discovered the electron and created plum pudding model
• Ernest Rutherford & Ernest Marsden


  discovered that an atom is mostly empty space

  
  

  scatter experiments at a thin sheet of gold
• Bohr


  discovered electron shells
• electron shells


  1st-2, 2nd-8, 3rd-8 to 18
• Dimitri Mendeleev


  Organized the periodic table of elements

  
  

  mainly by atomic number

  
  

  left gaps and predicted new elements
• Electrons


  react to form outer shells
• Group 1


  1 electron in outer shell

  very reactive

  soft

  gets more reactive as you go down

  lower melting and boiling points

  higher relative atomic mass
• alkali metals


  lose electrons easily to make ionic compounds
• Group 1 reaction with water

  produces hydrogen gas
• group 1 reaction with chlorine

  produces salt
• Group 1 reaction with oxygen


  produces metal oxide
• group 7 (halogens)


  as you go down:

  become less reactive

  have higher melting and boiling points

  have higher relative atomic masses
• Fluorine (F)


  Poisonous yellow gas
• Chlorine (Cl)


  fairly reactive, poisonous dense green gas
• Bromine (Br)


  poisonous red-brown volatile liquid
• Iodine (I)


  dark grey crystalline solid

  purple vapour
• Halogens can form...


  molecular compounds
• halogens form _________ when combined with metals

  ionic bonds
• More reactive halogens will...


  Displace less reactive ones
• Group 0 elements


  boiling points increase as you go down
• Ions are formed when

  Atoms gain or lose electrons
• group 1 & 2 form (metals)

  positive ions due to losing electrons
• group 6 & 7 (non metals)

  form negative ions due to losing electrons
• Dot and cross diagrams show

  how ionic compounds are formed
• what structure do ionic compounds have

  regular lattice structures
• Examples of giant covalent structures

  Diamond, graphite, silicon dioxide