Atomic structure

• what is a compound

  2 or more types of atoms chemically bonded
• what is an element

  1 type of atom
• what is a mixture

  2 or more types of atoms which are not chemically bonded
• what are the processes of separating mixtures

  • filtration
  • evaporation
  • distillation
  • chromatography
• what is the result of evapouration

  • dry crystals
• what was the first model of the atom

  • john dalton's model
  • all matter is made of atoms which cannot be created or destroyed
• what was the second atomic model

  • JJ Thompson
  • Plum Pudding model
  • negative electrons embedded in a ball of positive charge
• what did jj discover

  electrons
• what was the third atomic model

  • earnest rutherford
  • used the alpha particle experiment to create the NUCLEAR MODEL
• what did the alpha particle experiment show?

  • most of the atom is empty space BECAUSE most atoms went straight through the gold
  • however there is a dense center which has a positive charge
• what was the fourth atomic model

  • neils bohr adapted the nuclear model
  • suggested electrons are arranged in shells of energy levels
• what was the fifth version of the atomic model

  • ernest rutherford
  • nucleus contains small positive particles
  • protons
• what was the final discovery of the atom

  • james chadwick
  • nutral neutrons
• how big is the nucleus of the atom

  1 x10-10m = 0.1nm
• how is the periodic table arranged?

  • in order of atomic/proton number
  • groups - same properties and outer shell of electrons
  • periods - same numbers of electron shells
• how was the periodic table initially arranged

  • in order of atomic weight
  • many elements where misplaced as they didn't take into account properties
• how did mendeleev arrange his table

  • vertical columns - properties
  • horazntally - increasing atomic weight
• why did he leave gaps in the table?

  • he knew some elements that would fit the gaps where not discovered yet
  • he used the gaps to predict future elements
• what is group 0

  noble gases
• what are the noble gases

  • non metals
• what are the properties of noble gases

  • exist as single elements
  • colourless
  • unflammable
• why are noble gases unreactive/inert

  • they have a full shell of outer electrons
• why does the mpt and bpt increase down group 0

  • the atoms get larger down the group
  • increase in intermolecular forces
  • meaning an increased amout of energy is required to break them
• what is group 1

  alkali metals

  they form alkaline solutions when mixed with water
• why does group 1 metals have similar properties

  all have 1 outershell of electrons
• what are some group 1 metal properties

  • soft
  • low mpt
  • low density
  • very reactive as they only have to loose 1 electron to become stable
• why does group 1 metal mpt decrease down the group

  • atoms get larger
  • more shells meaning the forces of attraction decrease
  • less energy required to break them
• what are the first 3 alkali metals?

  • Lithium
  • sodium
  • potassium
• how does lithium react with water

  • fizzes
  • slowly moves on surface of water
• how does sodium react with water

  • more vigourous fizzing
  • moves rapidly on surface
  • dissolves
• how does potassium react with water

  • bruns with a lilac flame
  • moves rapidly on surface
  • dissolves quickly
• what are the group 7 elements

  • halogens
• what are properties of group 7 elements

  • non metals
  • poisonous
  • diatomic
• fluorine properties

  • yellow gas
  • very reactive
• chlorine characteristics

  • pale yellow green gas
  • reactive
• characteristics of bromine

  • red brown liquid
  • volatile
  • dense
• iodine charactaristics

  • grey solid
  • shimmery
  • sublimes to form a purple vapour
• why does bpt increase down the halogens

  • intermolecular forces increase as atom gets bigger so more energy is required to break them
• why does reactivity of halogens decrease down the group

  • number of electron shells increase so forces of attractions decrease meaning its less easy for the atom to gain 1 electron
• when does a halogen displacement reaction occur

  • a more reactive halogen displaces less reactive halogen from its halide
  • (chlorine is most reactive and iodine is least)