Chemistry paper 1

• metal displacement reactions can be used to extract metals from ores
• in the reactivity series, more reactive metals are above less reactive ones
• the reactivity series is the relative ability of metals to displace other metals from their compounds
• Atsic Structure and the Periodic Table
• Atoms, Elements, Compounds and Mixtures
• Atoms, Elements and Compounds
• Equations can describe what has happened during chemical reactions
• The total mass of the products of a chemical reaction is equal to the total mass of the reactants
• The products of a chemical reaction are made from exactly the same atoms as the reactants
• When magnesium burns, magnesium oxide is produced
• Word equation


  Describes the substances that react (reactants) and the new substances that are formed (products)
• Scientific Models of the Atom have changed over time
• Chadwick provided evidence that the nucleus contains protons
• Atoms contain three types of subatomic particles: protons, neutrons and electrons</b>
• Subatomic Particles


  • Proton: Relative mass 1, Relative charge +1
  • Neutron: Relative mass 1, Relative charge 0
  • Electron: Relative mass almost 0, Relative charge -1
• The radius of the nucleus is less than 1/10,000 of the atomic radius of the atom, so most of an atom is empty space
• Isotopes


  Atoms of the same element with the same number of protons but different numbers of neutrons
• Ions


  Atoms that have gained or lost electrons, giving them an overall charge
• Electron configuration

  Shows how the electrons are arranged around the nucleus
• The periodic table was developed over time as new elements were discovered
• Mendeleev arranged the elements in order of increasing atomic weight, which created some anomalies
• The periodic table is now arranged in order of increasing atomic number, which resolves the anomalies
• Group 0 (Noble Gases)

  • Have a full outer shell of electrons, making them very stable and unreactive
  • Boiling points increase down the group
• Group 1 (Alkali Metals)


  • Have one electron in their outer shell
  • Have low melting and boiling points that decrease down the group
  • Become more reactive down the group as the outer electron is further from the nucleus
• Alkali metals are stored under oil because they react very vigorously with oxygen and water
• When alkali metals react with water, a metal hydroxide is formed and hydrogen gas is given off
• Transition Metals


  • Form coloured compounds
  • Have multiple possible charges
  • Can be used as catalysts
  • Are good conductors of heat and electricity
  • Are stronger, harder, denser and have higher melting points than alkali metals
• The three states of matter are solid, liquid and gas
• Particle model

  Describes the arrangement and movement of particles in the three states of matter
• When a substance changes state, the particles themselves stay the same but the way they are arranged and move changes
• The melting point and boiling point of a substance depend on the strength of the forces of attraction between the particles
• Ionic compounds, metals and giant covalent structures have high melting points due to strong bonds
• State symbols


  Indicate the state of a substance in a chemical equation (s = solid, l = liquid, g = gas, aq = aqueous)
• Chemical bonds hold atoms together in compounds
• Ionic bond


  Forms between a metal atom that has lost electrons and a non-metal atom that has gained electrons, creating oppositely charged ions
• Formation of an ionic compound (sodium chloride)

  1. Two sodium atoms each lose one electron to form Na+ ions

  2. One chlorine molecule gains two electrons to form two Cl- ions

  3. The Na+ and Cl- ions are attracted to each other by strong electrostatic forces, forming the ionic compound sodium chloride
• Properties of ionic compounds

  • Are giant structures of ions held together by strong electrostatic forces
  • Do not conduct electricity when solid, but do conduct when molten or in solution as the ions are free to move
• Metallic bonding


  Involves a giant structure of positive metal ions with delocalised electrons in the outer shell that are free to move, giving metals their characteristic properties
• Metals conduct electricity well due to their metallic bonding
• Alloys are made by combining metals to improve their properties