Atomic structure & periodic table

• Atoms - all substances are made of atoms which are the smallest parts of an element that can exist
• relative charge

  Proton = +1

  Neutron = 0

  Electron = -1
• relative mass

  proton - 1

  neutron - 1

  electron - very small or 0
• Mixture consist of two or more elements that are not chemically combined together
• The separating techniques for mixtures include fractional, distillation, chromatography, crystallisation, filtration & simple distillation
• Crystallisation

  We place our solution on top of a Bunsen burner in which it is heated up & then evaporates in which we see Crystal start to form, and it becomes insoluble. Then we take oscillation off the heat and leave it to cool. And watch more crystals start to fall and then we filled her out the remaining solution and then we leave in a warm place to dry
• Simple distillation

  We heat up our solution in which the lower boiling point of the solution evaporates first. And the vapour is then cooled & condenses. Then the rest of the solution is left in the flask
• Why use pencil For your line in chromatography?

  As pencil is insoluble and won’t dissolve in the solvent
• why the new evidence from the scattering experience letter change in atomic model

  Ernest Rutherford said that the mass of an atom was concentrated in the nucleus, and the nucleus was charged. Therefore replacing the plum pudding model
• Plum pudding model

  jj Thomson came up with the plum pudding model in which show the atom of a ball of positive charge with negative electrons embedded in it
• The Nuclear model Bohr Suggesting that electrons orbit, the nucleus in specific distances
• The difference between the plum pudding model & nuclear model of the atom


  -The nuclear model has many empty spaces

  -nuclear model only has positive charge in the nucleus

  -nuclear model had electrons in shells

  -nuclear model has the mass concentrated at the nucleus
• Use the nuclear model to describe

  In the nuclear model the mass of the atom are located in the nucleus at the centre
• Atoms radius = 0.1nm (1x10^-10m)
• nucleus radius = (1x10^-14m)
• explain how the position of an element in the product table is related to the arrangement of electrons in its atom, and hence to its atomic number


  The group in which an element is in shows how many electrons are on its outer shell & They have similar properties to other elements in the same group
• Steps in the development of the periodic table

  1. In the 1800 they had no idea about the atomic structure e.g protons atomic number, neutron etc

  2. They measured an atoms weight & arranged electrons in atomic weight

  3. When this was done, they found a period pattern in the properties of elements & so named it "the periodic table"

  4. And when they had made the parent table, the properties of elements were not taken into account just atomic weight

  5. Mendeleev wanted to overcome these issues in the early periodic table

  6. He arranged the table in order of increasing atomic weight

  7. He left gaps as some electrons had not been discovered yet

  8. He made sure elements of the same properties were in the same group
• In the modern periodic table, everything is ordered by atomic number & every element is in the correct group
• Metals are found on the left-hand side of the periodic table & react to form positive ions
• Nonmetals are found on the right-hand side of the periodic table & dont form to make positive ions
• Metals

  • Metallic bonding (very strong)
  • Conductors of heat
  • High boiling & melting point
• Non - metals

  • Brittle (easy break)
  • Low boiling & melting point
  • dull in colour
• For metals it is much easier to form positive ions as metals don’t have a full outer shell & electrons are far from the nucleus meaning there is a weak attraction & so not much energy is needed to remove electrons & form positive ions
• For non-metals it is much harder & difficult to form positive ions as they have a full outer shell & electrons are close to the nucleus making a strong attraction in which requires lots of energy. Therefore it’s hard to remove, gain or share electrons of non mentals
• Group 1 (Alkali metals)
• Group 1 as you go down the group, the reactivity increases & the electrons get further away from the nucleus
• Trends as you go down group 1

  • Lower boiling & melting point
  • Higher relative atomic mass
  • Reactivity increases & electrons get further away from nucleus
• Alkali metals react with water to produce hydrogen gas & react vigorously. As you go down the group the reactions become more violent
• Alkali, metals, react with chlorine to produce metal chlorides which are white salts. These reactions become more vigorous as you go down the group
• Alkali ,react with oxygen in the air to form metal oxide, which is why alkali metals tarnish when exposed to the air
• Group 7 (halogens) non metals
• All halogens(group, 7) exist as pairs of atoms
• Trend as you go down group 7

  • Less Reactivity
  • Higher boiling & melting
  • higher relative atomic mass
• Group 7 elements form covalent, compounds, when reacting with other non-metal elements
• The halogens react with metals they form ionic compounds
• When any halogen reacts with a metal the halogen atom gains one electron & forms an ion with a -1 charge in which the name of the halogen now ends with ide
• More reactive halogens can displace less reactive halogens from an aqueous solution of its salts
• Group, 0 (noble gases) group is non-metal
• Trend in group, 0

  • Increasing boiling point
  • Increasing relative atomic mass
• Crystallisation - separate soluble salt from a solution