GCSE chemistry

• Malleable


  hammered into shape
• Ductile


  Pull into wire
• Sonoras and three others

  Sonorous-nice sound when hit

  conduct electricity

  Conducts heat

  High melting/boiling point
• GHDSFM

  G-gas bubbles made

  H-heat is made

  D-disappearing solid

  S-solution colourless

  F-floats

  M-melts
• Element- state at room temperature -colour


  Fluorine- Gas-pale yellow

  Chlorine- Gas- pale green

  bromine- liquid - red/brown

  iodine- solid- Dark grey
• Sublimation


  Sublimation occurs when when a solid goes directly to Gas. Iodine is a grey solid at room temperature and when gently heated produces a deep purple vapour.
• Test for chlorine gas

  Damp universal indicator is used. Chlorine turns it red then Bleach white.
• Group 0-noble gases

  They are colourless, odourless gases

  Noble gases are inert (un reactive) as they have a full outer shell of electrons and are stable without reacting with something else.
• Transition elements


  Transition elements from ions for different charges and form coloured compounds.

  Copper oxide-black

  Copper carbonate-green

  hydrated copper sulphate-blue

  Copper salts- blue
• Atomic structure

  Atoms are made of a very small nucleus, containing neutrons and protons with negatively charged electrons in shells orbiting the nucleus.
• Name the particle-mass-charge

  Proton- 1 - +1

  Neutron- 1 - 0

  Electron- 1/1840 - -1 (almost 0)
• What does the top number of an element represent?

  Relative atomic mass(AR)

  Mass number( protons and electrons)
• What does the bottom number of an element represent?

  Atomic number (number of protons or electrons)
• Atom


  An atom does not have a charge because the number of protons is equal to the number of electrons.
• Element definition

  Only one type of atom
• Compound


  More than one type of atom chemically combined
• Mixture


  More than one type of atom, not chemically combined.
• Isotopes

  Isotopes are the same element with the same atomic number, but a different mass number. This means the numbers of neutrons varies. Isotopes have the same number of protons and electrons so do not have a charge.
• Ionic bonding

  Occurs between metals and nonmetals

  Attraction between oppositely charged ions
• Bonding-how the ions are held together

  Electrostatic attraction

  Lots of energy required to break ionic bonds
• Structures-physical properties (think salt)

  High melting/boiling point

  hard brittle and crystalline

  soluble in wate does not conduct electricity as a solid

  Conducts when molten or dissolved
• Covalent bonding

  Between nonmetals

  Electrons are shared to create full outer shells

  A single covalent bond is when 2 electrons are shared, double when 4 shared
• Molecule


  A molecule is two or more atoms covalently bonded
• Diatomic molecule


  Diatomic molecule means two atoms covalently bonded in a molecule. For example F2, Cl2, Br2 and I2
• Bonding- how atoms are held together

  covalent bonds are strong and need a lot of energy to break

  The intermolecular forces between covalent molecules are weak forces called Van der waals forces. (Low melting/boiling point)
• Structures


  Covalently bonded elements from molecular covalent structures or giant covalent structures.
• Molecular covalent structure properties (gas)

  Low melting/boiling point

  Doesn’t conduct electricity( no free electrons)

  Low solubility in water
• Giant atomic structures and allotropes

  Diamond, graphite and graphene are all allotropes of carbon.

  another troop is a different form of the same element in the same physical state.
• Pure substances

  A pure substance is a single element or compound, not mixed with any other substance.

  Pure elements and compounds melt and boil at specific temperatures, melting and boiling points can be used to distinguish pure substances from mixtures.
• Formulations

  A formulation is a mixture that has been designed as a useful product and is formed by mixing together

  Several different substances in carefully measured quantities to ensure the product has the required properties for example, alloys, medicines and fertilisers.
• Crystallisation and saturated solution


  A saturated solution is one in which no more solid can dissolve at that temperature. It is the maximum mass of dissolved substance.

  many salts, copper (11) sulphate are separated from their solution by crystallisation.
• What is the solvent front?

  The solvent front is the furthest distance travelled by the solvent
• Paper chromatography


  Chromatography can be used to separate mixtures of soluble substance substances in solution.
• how chromatography works?

  In paper chromatography, the stationary phase is the paper in the mobile phase is the solvent.
• Testing for water

  Add a few drops of the liquid into anhydrous copper sulphate (copper (11) sulphate) in a test tube. If water is present, then hydrated copper sulphate is made. anhydrous copper sulphate is white and hydrated Copper sulphate is blue.
• nichrome wire test

  Dip nichrome wire into concentrated hydrochloric acid (HCL) to clean the wire.

  Play solar into a blue Bunsen flame
• flame colour test

  Li+ - crimson

  Na+ - yellow/orange

  K+ - lilac

  Ca+ - brick red

  Cu+ - blue/green

  Ba+ - green
• Diamond


  Each carbon atom is covalently bonded to 4 more carbons. 3 dimensional structure
• What do the dots and lines represent?


  each dot represents a carbon atom. Each line represents a covalent bond.
• Physical properties of diamond and the uses

  Hard solid and giant covalent structure has strong covalent bonds

  very high melting/boiling point

  lots of strong covalent bonds in giant structure needs lots of energy to break

  Doesn’t conduct electricity

  Insoluble in water

  Used in cutting tools because it is hard.