Chemistry

• rutherfords nuclear model 


  1909- Ernest Rutherford

  discovered alpha particles could bounce back off atoms.

  atoms mass was im the centre was called a nucleus, it contained protons
• Plum pudding model 


  1897- JJ Thompson

  discovered electrons

  ball of positive charge (dough)

  negatively charged electrons (currants)
• Modern model

  • Niels Bohr discovered that electrons orbit (fly around) the nucleus at fixed distances.
  • In 1932, James Chadwick discovered that some particles in the nucleus have no charge at all. He called them neutrons.
• Mass 


  Top number

  protons and neutrons
• Atomic number

  bottom number

  Protons
• Newlands' periodic table

  • John Newlands was the first chemist to devise a periodic table.
  • Newlands' periodic table was ordered by the mass of the element.
  • But, the table was incomplete, and some elements were placed in inappropriate groups.
• Mendeleev's periodic table

  • Dmitri Mendeleev recognised that there may be undiscovered elements.
  • Mendeleev added gaps to Newlands’ table to account for undiscovered elements.
  • Mendeleev even predicted the properties and masses of these undiscovered elements!
• The modern periodic table

  • The discovery of protons and isotopes has shown that Mendeleev ordered elements exactly by relative atomic mass.
  • Therefore, the modern periodic table looks very similar to Mendeleev's (except the gaps are filled)
• Displacement reaction

  When a less reactive halogen (one lower down the periodic table) is displaced by a more reactive halogen from a compound.
• Ionic bonding

  • Ionic bonding involves an attraction between oppositely charged ions.
  • Ionic bonds are found in compounds made of metals and non-metals
• Covalent bonds

  • Covalent bonding involves 2 atoms sharing 1 or more pairs of electrons.
  • Covalent bonds are found in non-metal elements and in non-metal compounds.
• Metallic bonding

  • Metallic bonding involves an attraction between positively charged ions and negatively charged delocalised electrons. 
  • Metallic bonds are found in metals and alloys
• Ionic lattices 


  Giant structures that are held together by strong electrostatic forces between positively and negatively charged ions.
• Structure of Pure Metals

  • Pure metals have giant structures with strong electrostatic forces between positive ions and delocalised electrons.
  • All ions are the same size and they are arranged in layers.
• Alloys

  • An alloy is a combination of 2+ elements, where at least 1 is a metal.
  • The ions of the different elements are different sizes. 
  • This makes it harder for the layers to slide across each other when a force is applied to the alloy. 
  • This makes alloys stronger than pure metals, and so they are often used in construction.
• Alkane structure

  • In alkanes, carbon atoms bond to four atoms (hydrogen or carbon). 
  • We call them saturated hydrocarbons as all their bonds with other atoms are single bonds.
  • Alkanes have quite low reactivity, but they combust quite well.
  • Alkanes have the general formula CnH(2n+2)
• Fractional Distillation

  Fractional distillation is the process of separating crude oil into groups of hydrocarbons with similar numbers of carbon atoms. We call these groups of hydrocarbons “fractions”.
• Alkenes

  Alkenes are hydrocarbons with the functional group C=C. This means that alkenes have a carbon-carbon double bond.