Chemistry

• what is an atom?

  The smallest part of an element
• What is an element?

  A substance made up of only one type of atom
• Evaporation separates:


  A solid dissolved in a solvent
• Fractioning column is 


  Hot at the bottom and cooler at the top
• why are atoms electrically neutral

  same number of protons and neutrons
• Atomic number = 


  No. of protons
• Atomic mass = 


  no. of protons + neutrons
• what are ions? 


  chargerd particles
• Metals V Non-Metals

  Metals:

  1. High boiling and melting points
  2. Conduct heat and electricity
  3. Maleable
  4. Shiny
  5. dense
• Metals V Non-Metals: 


  Non-Metals

  1. low melting and boiling points
  2. Doesn't conduct (except graphite)
  3. Dull
  4. Brittle
  5. not dense
• Ionic bonding = 


  Metal + Non-metal

  Electrostatic attraction between positive and negative ions
• Covalent bonding = 


  Non-metal + Non-metal

  (sharing electrons)
• Solute = 


  The thing that dissolves
• Solvent =


  the thing it dissolves in
• Solution = 


  Solute + Solvent
• Soluble = 


  can dissolve in a solvent
• Insoluble = 


  won't dissolve in a solvent
• How was the periodic table first arranged?

  1. Atomic weight
• Mendeleev's advancement?


  He left gaps for undiscovered elements and put the rest In order of atomic weight and chemical properties
• What showered Mendeleev was correct?

  The discovery of the isotope
• Elements that form positive ions are..


  Metals
• Group 1 elements are known as

  the alkali metals
• The alkali metals..


  have 1 electron in their outer shell (very reactive)

  Soft

  low density

  reactivity increases + melting and boiling point decreases going down.
• Group 1 + Non metal = 


  Ionic compound
• Group 1 + water =

  react vigorously

  fizzing
• Group 7 = 


  Halides

  reactivity decreases + melting and boiling point increases going down

  Colourful vapour
• Group 7 elements and their vapours 


  Fluorine = Poisonous Yellow gas

  Chlorine = Poisonous Dense green gas

  Bromine = Poisonous red- brown volatile liquid

  Iodine = dark grey solid / purple vapour
• Group 1 v transition metals

  Transition metals are denser, have higher melting and boiling points are less reactive and are harder.
• Three common characteristics of transition metals

  Ions with different charges

  coloured compounds

  catalytic properties
• Lithium -> 


  Crimson
• Sodium -> 


  Yellow
• Potassium ->


  Lilac
• Group 0 or Noble gases

  unreactive

  Non metals

  low boiling points

  boiling point increases going down
• Simple covalent structures ->


  Soft

  weak intermolecular forces

  low melting and boiling points

  Do not conduct electricity
• Large covalent structures ->


  Giant lattice

  strong intermolecular forces

  High melting and boiling points

  Diamond, graphite and silicon dioxide
• What is a polymer?

  A very large molecule with atoms linked by covalent bonds
• Graphite properties 


  sheets of hexagons

  each carbon has only 3 covalent bonds

  (1 delocalised electron to conduct electricity)

  no bonds between layers - free to move over each other-

  high melting point
• Diamond properties ->


  Hard

  High melting point

  Giant lattice

  Each carbon atom has 4 covalent bonds

  No conductivity
• Alloys ->


  Mixture of metals
• Why are Alloys hard?

  different sizes of atoms distorts layers so they can not slide over each other