Paper 1 chemistry

• What were the early periodic table

  Incomplete with some elements placed in inappropriate groups
• What did mendeleev do to overcome problems with the pt

  Left gaps for undiscovered elements

  Changed order of some places based on atomic weight.
• What are metals 


  Elements that react to form positive ions
• What are non metals

  Elements that do not form positive ions
• What are group 0 elements known as and what are their properites

  Noble gases, unreactive don't form molecules easily

  Bpt increases going down
• What are the properties of group 1 metals

  Alkali , single electron on outer shell

  Reactivity increases going down.
• What are the properties of group 7

  Halogens, seven on outer shell. Mr, mpt and bpt increases whilst reactivity decreases going down
• What are the relative electrical charges of particles

  Proton = 1

  Neutron = 0

  Electron = -1
• What is the radius of an atom 


  1 x 10‐¹⁰ m
• What are the relative masses for subatomic particles

  Proton = 1

  Neutron = 1

  Electron = 1/2000 (almost 0)
• What is an atom 


  Smallest part of an element
• What is a compound 


  Two or more elements chemically combined together in fixed proportion
• What are mixtures 


  Consist of two or more elements or compounds NOT chemically combined together
• How can mixtures be seperated

  Physical processes such as filtration, distillation and crystallisation
• What were atoms thought to be before the discovery of the electron

  Thought to be tiny spheres that could not be divided.
• What did JJ Thomson discover

  Atom - ball of positive charge with negative electrons embedded in it - plum pudding model
• What did Ernest Rutherford's alpha scattering experiment lead to

  Mass of an atom was concentrated at the centre - nucleus and that nucleus was charged
• What replaced plum pudding

  Nuclear model adapted by Niels Bohr - suggested electrons orbit nucleus at specific distances
• Who discovered the proton

  Ernest Rutherford
• Who discovered the existence of neutrons

  James Chadwick
• Largest small covalent molecule


  Methane with 5 atoms
• Key properties of small covalent molecules

  Low melting and boiling points which means they are usually gases or liquids at room temperature

  
  

  They do not conduct electricity
• Why do small covalent molecules not conduct electricity?

  the molecules do not have an overall electric charge
• Why do small covalent molecules have low melting and boiling points?

  In liquid form the covalent molecules would vibrate and move from place to place. The atoms in each molecule are held together by very strong covalent bonds There are very weak intermolecular forces between molecules. As we increase the temperatures the molecules increase in vibrations and at a certain point this vibration is strong enough to break the weak intermolecular forces holding the molecules to each other. The molecules boil and turn to a gas at this point. Not a lot of energy is required to break these intermolecular forces
• What happens to the intermolecular forces as we increase the size of the covalent molecule

  They increase
• Properties of simple covalent molecules

  strong bonds between atoms i. the molecule but weak intermolecular forces between the molecules which cause for a low mp and bp and are usually has and liquids at room temperature
• what is a polymer


  long chain of monomers(molecules that bond to other identical molecules )
• type of bonding in polymers

  simple covalent
• polymers mp and bp

  the molecules are quite long so there are more intermolecular forces between the molecules and these intermolecular forces are relatively strong so more energy required to overcome all of these intermolecular forces of attraction so a high bp and mp
• what are polymers usually at room temperature

  solid
• can simple covalent molecules dissolve in water


  sometimes
• What are isotopes

  Atoms of same element different mass number and different neutron number
• What are properties of diamond

  4 covalent bonds with other carbon atoms so diamond is very hard, has a very high melting point and does not conduct electricity
• What are the properties of graphite 


  Each carbon atom forms 3 covalent bonds with 3 carbon atoms - forms layers of hexagonal rings no covalent bonds between layers. Delocalised electron from each carbon