Chemistry paper 1

• What is an atom?


  An atom is the smallest part of an element, that can exist
• What are the Polyatomic ions?


  Hydroxide, Nitrate, Sulfate, Carbonate.
• What is ionic bonding?


  Occurs between metals and non-metals
• What is an ion?


  Charged particles formed from the gaining or losing of outer electrons
• When is a covalent bond formed?


  Formed when two or more non-metals share pairs of electrons
• What are Polymers?


  Polymers are large molecules containing chains of carbon atoms.
• What is a base?


  Any substance that reacts with an acid to form salt+water. This is a neutralisation reaction.
• Why can't ionic compounds conduct electricity as a solid?


  When they are a solid the ions are not free to move so when the ionic compounds are dissolved in water the ions are free to move and now electricity can be conducted.
• What is electrolytes?


  Substances which can be broken down by electrolysis.
• Define what an isotope is


  Isotopes are different atoms of the same element containing the same number of protons but different numbers of neutrons in their nuclei.
• Why are metals good conductors of electricity?


  The delocalised electrons can move through the lattice of ions.
• What does a mixture contain?


  A mixture contains different elements or compounds but they are not chemically combined.
• How can mixtures be separated?


  Using physical seperation techniques such as filtration, distillation, crystallisation or chromatography.
• Definition of Electrolysis


  Using electrical energy to break things down
• What are electrostatic forces of attraction?


  Attraction between positive and negative charges
• Order of reactivity

  Potassium, Sodium, Calcium, Magnesium, Aluminum, Zinc, Iron, Copper, Silver, Gold
• Describe the test to show if the gas is hydrogen


  Place a lighted splint in a test tube containing the gas. If there is a squeaky pop sound the gas is hydrogen
• What is a limiting reactant?


  The reactant that gets consumed first in a chemical reaction and therefore limits how much product can be formed.
• Explain why chlorine is a gas, rather than a liquid, at room temperature.

  It has a low melting point as the molecular forces are weak so little energy is needed to break them apart.
• What are allotropes?


  Different structural forms of the same element.
• Define an allotrope


  Different structural forms of the same element
• What is the name of group 7 elements?


  Halogens
• What are the three main stages of distillation?


  Boiling/evaporating, condensing, collecting
• Define an alloy


  Mixture of metals
• What is Corrosion?


  When a metal continues to oxidise and becomes weaker overtime
• What is rusting?


  Only the corrosion of iron - needs both oxygen and water
• Methods of preventing corrosion which create a barrier between the metal and the environment


  Coating metal in plastic, painting metal, greasing metal
• Meaning of a strong acid 


  An acid that has been fully ionised
• Meaning of a weak acid 


  An acid which has been partially ionised
• Describe an ionic bond


  Electrostatic attraction between positive ions and negative ions
• Why is electrolysis used to extract metals like aluminium from their ores? ( oxides )


  They are more reactive than carbon, so can't be extracted by heating with carbon.