CHEMISTRY PAPER 1 ALL I NEED TO KNOW

• Element 


  It’s an substance with one type of atom
• Compound


  Different types of atoms that chemically combined together
• Mixture 


  Combination of different types of atoms/compounds that are not chemical combined together
• Molecule


  Has any elements chemically combined
• Filtration 


  Used to separate insoluble solid from a liquid
• Crystallisation 


  Used to separate soluble solid from a liquid
• Why should you be careful while heating a solution in crystallisation?

  Molecules can break down
• Simple distillation 


  Used to separate liquid and dissolved solid
• What is stationary phase?

  The molecules that do not move
• Mobile phase

  When molecules move
• Alpha scattering experiment


  Some of the particles passed straight through

  Some of them were deflected

  Some of them bounced back
• Alpha scattering experiment results 


  It has mainly an empty space.

  The centre of the atom has a positive charge

  The centre of an atom contain a great deal of mass
• nuclear model


  has empty space

  have nucleus containing the most of the mass

  at the edge of the atom it has electrons
• Niel Bohr said that the electrons orbit the nucleus at the specific distances
• Proton


  Proton then has been discovered in the centre of an atom
• James Chadwick


  Discovered neutral particles - neutron
• Radius of an atom

  1 x 10 (-10)m
• Radius of the nucleus 


  1 x 10(-14)m
• Ions


  Atoms that have an overall charge
• Relative atomic mass


  The average mass of all the isotopes and the abundance
• Dobereiner Triads 


  put the elements in threes because they have similar chemical properties
• Newlands Octaves 


  He arranged elements in order of their increasing atomic weight and saw that every eighth elements have similar properties
• Problems of Newlands Octaves

  The every eighth elements sometimes had totally different properties
• Mendeleev 


  He arranged the elements in order of their atomic weight .

  He switched the elements so the elements fit the pattern .

  He left gaps because he knew that some of the elemets had not been discovered yet.
• Modern periodic table


  arranged in order of atomic number
• Group 1 elements


  Soft metals

  Low melting point

  Low density

  React rapidly with water, oxygen and chlorine

  Form ions with 1+ charge.

  Boiling point decreases going down the group
• Transition metals properties 


  Hard and strong metals

  Hight melting points

  High density

  Much less reactive than group 1 metals
• Solids

  Solids are extremely hard to compress because They have a regular pattern and almost no spaces between them . They have a fixed shape so they cannot flow from place to place but they can vibrate
• Liquid

  Liquids are extremely hard to compress because the particles are close together and not many spaces between them but they can flow from place to place
• Gases

  Extremely easy to compress because they are wisely spaced . Gases can move randomly and quickly
• Limitations of the simple particle model

  It assumes that the particles are solid spheres .

  There are not forces between the particles
• Properties of Ionic Bonding


  Giant ionic lattice

  A strong electrostatic forces of attraction

  Have high melting/boiling point

  Only conduct electricity when molten/ dissolved in water
• Properties of small covalent molecules

  Low melting/boiling points because of weak intermolecular forces
• Diamond

  Carbon atom form 4 covalent bonds

  High melting/boiling point

  Cannot conduct electricity
• Silicon Dioxide

  Contains silicon and oxygen that covalently bonded together . Has a high melting/boiling point
• Graphite properties


  Soft and slippery

  High meting/boiling point

  Good conductor of heat and electricity(delocalised electrons between the layers , they can move so they can conduct thermal energy and electricity)
• Structure of graphite


  Each carbon atom form three covalent bonds . So it forms hexagonal rings . Hexagonal rings are arranged in layers( there are no covalent bond between the layers, thats why its soft and slippery )
• Use of graphite 


  Lubricant in machines reducing friction
• Graphene


  One atom thick
• Properties of graphene 


  Good conductors of electricity and heat because it has delocalised electrons . These electrons move through the graphene carrying electrical charge