Chemistry paper 1

• Atoms

  • All substances are made up of atoms.
  • The periodic table lists all chemical elements that are split into 8 groups.
  • Elements contain only one type of atom.
  • Compounds contain more than one type of atom.
• Atomic Structure

  • Atoms are made up of a nucleus which is made up of protons(+1) and neutrons(0).
  • They also have shells that hold the electrons(-1)

  Relative mass:

  • Protons = 1
  • Electrons = 0
  • Neutrons = 1
• Atomic Number and Mass

  • The atomic number is found above the symbol.
  • The atomic mass is found below the symbol.

  Number of protons = atomic number

  Number of electrons = atomic number

  Number of neutrons = atomic mass - atomic number
• History of the Atom

  Solid sphere model:

  • Discovered by John Dalton.
  • Recognised that atoms of a particular element differs from other elements.
  • His theory stated that atoms are invisible which is incorrect.

  Plum pudding model:

  • Discovered by J.J. Simpson.
  • He discovered electrons and his model showed them scattered in a positively charged sphere.

  Nuclear model:

  • Discovered by Ernest Rutherford.
  • He discovered the nucleus using the alpha particle scattering experiment.

  Planetary model:

  • Discovered by Niels Bohr.
  • Stated the structure and function of electrons.
• Chemical Reactions

  • Atoms can not be created or destroyed.
  • Total number of reactants = total number of products.
  • Balanced symbol equations have the same number of atoms on each side.
  • State symbols can be added to symbol equations.

  (S) = Solid

  (L) = Liquid

  (G) = Gas

  (Aq) = Aqueous Solution
• Separating Mixtures

  A mixture is made up of two or more substances but are not chemically combined together.

  • Soluble = dissolvable
  • Solvent = the liquid in which a substance is dissolved
  • Solution = mixture of two or more substances.
• Filtration

  • Used to separate substances that are insoluble in a particular solvent from those that are soluble.
  • It involves a circle filter paper folded to make a cone and placed in a filter funnel.
  • One beaker contains a mixture of solid and liquid, the other contains a funnel with filter paper.
  • The solid and liquid mixture is poured into the filter funnel.
  • The liquid drips through the filter paper but the solid particles are caught in the filter paper.
• Crystallisation

  Is used to produce solid crystals from a solution. When the solution is warmed. some of the solvent evaporates leaving behind a concentrated solution.

  • A solution is placed in an evaporating basin and heated with a Bunsen burner.
  • The volume of the solution has decreased because some of the water has evaporated. Solid particles begin to form in the basin.
  • All the water has evaporated leaving crystals behind.
• Simple Distillation

  Its used to separate a solvent from a solution.

  • Salty water is heated.
  • The water vapour cools in the condenser and drips into a beaker.
  • The water has condensed and is now in the beaker, the salt stays behind.
• Fractional Distillation


  Is used to separate different liquids from a mixture of liquids. When the mixture is heated:

  • Vapours rise through a column which is hot at the bottom and cooler at the top.
  • Vapours condense when they reach a part of the column that is below the temperature of the boiling point.
  • Each liquid is led away from the column.
  • The separation is possible because of the different boiling points of the liquids in the mixture.
• Ion

  • Atoms that gain an electron form negative ions.
  • Atoms that lose an electron form positive ions.
• Isotopes

  • Atoms of the same elements with different numbers of neutrons.
  • They have identical chemical properties but their physical properties can differ.
• Electronic Structures

  • The electron in an atom are arranged in energy shells.
  • 1st shell = two electrons.
  • 2nd and 3rd = eight electrons.
• Periodic Table

  • Rows of elements are called periods.
  • Columns of elements are called groups, there are 8.

  Mendeleev:

  • The elements are arranged in order of increasing atomic mass.
  • Elements in the same group are similar to each other.
  • He left gaps for elements that had not yet been discovered.
• Group 1 - Alkali Metals

  • Melting and boiling points decrease as you go down the group.
  • The metals all react with water to produce hydrogen and an alkaline solution containing the metal hydroxide.
  • They form +1 ions in reactions to make ionic compounds.
  • The reactivity of alkaline metals increases going down the group.
  • They are very soft.
  • They have low densitys.
• Group 7 - The Halogens

  • They have low melting and boiling points that increase as you go down the group.
  • They are poor conductors for heat and electricity.
  • Reactivity decreases as you go down the group.
  • The halogens all form ions with a single negative charge in their ionic compounds with metals.
  • They form covalent compounds by sharing electrons with other non-metals.
  • A more reactive halogen can displace a less reactive halogen from a solution of one of its salts.
• States of Matter

  Solid:

  • Packed closely together.
  • Vibrate around a fixed position.
  • High density.

  Liquid:

  • Are close together but can slide over each other in random motions.
  • High density.

  Gas:

  • Free to move rapidly and randomly.
  • Low density.

  Energy can be transferred between states via melting, boiling, freezing and condensing.
• Element


  A substance containing only one type of atom.
• Compound

  A substance containing two or more different types of atoms chemically bonded.
• Mixture

  Different substances not chemically bonded.
• Metallic Bonding

  • Metal + Metal
  • They form a lattice of ions surrounded by a sea of delocalised electrons.
  • Because the electrons are free to move, they make good conductors for electricity and heat.
• Ionic Bonding

  • Metals + non-metals
  • Metal ions donate electrons to non-metals to form ions.
  • Dot and cross diagrams show the electrons on the outer shells.
  • Metals always end up with an empty outer shell, non-metals with 8 electrons.
  • The charges of all ions must add up to zero.
• Ionic structures

  • Ions are arranged in a lattice of repeating units of positive and negative ions, these form crystals.
  • Ionic substances have high melting and boiling points due to the strong ionic bonds (as the ions have strong electrostatic forces between them).
  • They conduct electricity when molten or in solution because ions are free to move in these states, and they carry charge.