Paper 1 from miss salis

• Element


  A substance that is made up of only one type of atom
• Compound


  A substance made up of two or more different elements bonded together
• Structure of the atom

  • In the centre there is a nucleus made up of protons and neutrons
  • Electrons orbit the nucleus

  
• Atomic mass


  Neutron + protons
• Electron arrangement


  1. Electrons will fill the shell closest to the nucleus first

  2. Each shell can hold a specific number of electrons

  3. 1st shell = 2

  4. 2nd shell = 8

  5. 3rd shell = 8
• Isotope


  • Atoms of the same element with different numbers of neutrons
  • Isotopes will have the same number of protons and electrons
• Rutherford's experiment


  • Fired alpha particles at gold foil
  • Most alpha particles passed through, but a few were deflected
  • Proved atomic structure was mainly empty space with a small, positively charged nucleus

  
• Mendeleev's Periodic Table


  • Arranged by atomic mass
  • Left gaps for undiscovered elements
• Modern Periodic Table


  • Elements are arranged by atomic number (proton number)
  • Elements in the same group have similar chemical properties
  • As you go down a group, the number of electron shells increases by 1
  • As you go across the Periodic Table, the number of electrons in the outer shell increases by 1
  • The group number indicates how many electrons are in the outer shell of an atom
• Ion


  A charged particle produced by loss or gain of electrons
• How an atom forms an ion

  1. Atoms lose or gain electrons

  2. Metals lose electrons and form positive ions

  3. Non-metals gain electrons and form negative ions
• Why atoms form ions

  Atoms will react to form ions to get a full outer shell of electrons
• Group 1 - The Alkali Metals


  • Soft
  • Low melting point
  • Low density
  • Conduct electricity
• Group 1 metals reacting with water

  1. pH of the solution increases (becomes alkaline)

  2. Fizzing/bubbling (H2 gas is produced)

  3. The metal floats on water (metal is less dense than water)

  4. The metal becomes a molten sphere
• Reactivity of Group 1 metals

  The Group 1 metals get more reactive down the group due to the outer electron being further away from the nucleus therefore weaker electrostatic attraction, so the electron is more easily lost
• Group 7 - The Halogens


  • Fluorine: Colourless gas
  • Chlorine: Pale-yellow gas
  • Bromine: Orange liquid
  • Iodine: Grey solid with a purple vapour
• Physical properties of Group 7 elements

  As you go down the group, colours get darker and boiling point increases
• Reactivity of Group 7 elements

  Halogens get more reactive up the group due to the outer electron shell being closer to the nucleus therefore stronger electrostatic attraction, electron is more easily gained
• Displacement reaction


  When a more reactive element takes the place of a less reactive element in a compound
• Group 0 - The Noble Gases

  They have a full outer shell of electrons and do not need to lose or gain any electrons, so they are unreactive
• Transition Metals


  • Hard
  • Conduct electricity and heat
  • High melting points
  • Malleable
• Reactions of transition metal compounds

  Transition metals will form coloured precipitates on addition of ammonia solution
• Reactions of Group 1, 2 and 3 metal compounds

  These metals will form colourless (white) precipitates on addition of ammonia solution
• Ionic lattice


  Positively charged metal ions and negatively charged non-metal ions
• Ionic compounds


  • Have high melting points
  • Cannot conduct electricity when solid
  • Can conduct electricity when either dissolved or molten
• Simple molecular structure


  • Strong covalent bonds between the non-metal atoms
  • Weak intermolecular forces between the molecules
• Simple molecular structures


  • Have low melting points
  • Do not conduct electricity
• Diamond


  • Has a high melting point
  • Is strong
  • Cannot conduct electricity
• Graphite


  • Has a high melting point
  • Is soft
  • Can conduct electricity
• Metallic lattice


  • Positive metal ions surrounded by a 'sea of electrons'
  • Metal ions are arranged in rows and are closely packed together
• Metals


  • Have high melting points
  • Can conduct electricity
  • Are malleable
• Reactions of Acids


  1. Metal + oxygen → metal oxide

  2. Metal + acid → metal salt + hydrogen

  3. Metal oxide/hydroxide + acid → metal salt + water

  4. Metal carbonate + acid → metal salt + carbon dioxide + water
• Acid used


  • Hydrochloric acid → chloride
  • Sulphuric acid → sulphate
  • Nitric acid → nitrate
• pH scale


  Measure of the acidity or alkalinity of a solution using a scale from 0 to 14 and can be measured using universal indicator or a pH probe
• pH scale


  • pH = 7 is neutral
  • pH value ≺7 is acidic
  • pH value ≻7 is alkaline
• H+ ion concentration


  As the H+ ion concentration of the solution increases by a factor of 10, the pH value decreases by 1 unit
• Strong acid


  Ionises completely in solution
• Endothermic


  A reaction that absorbs energy from the surroundings, causing a temperature decrease
• Exothermic


  A reaction that releases energy into the surroundings, causing a temperature increase
• Weak acid


  Only weakly ionises in solution