chem paper 1

• This is good for higher and Foundation Tier double combined Trilogy and triple separate chemistry that's topics 1 to five atoms bonding quantitative chemistry and chemical and energy changes
• Substances are made of atoms
• Element


  A type of atom represented in the periodic table by a symbol
• Compound


  A substance that contains two or more different types of atoms chemically bonded together
• Compound


  • Water (H2O)
• If there's no number after a symbol, there's an invisible 1
• Chemical reaction


  Atoms change what they're bonded to and how they're bonded
• Ways to represent a chemical reaction

  • Word equation
  • Chemical equation using symbols
• Balancing a chemical equation

  1. Start with atoms only in compounds

  2. Balance atoms that are only on one side

  3. Use numbers in front of elements/compounds to multiply
• Atoms are not created or destroyed in a chemical reaction, the same number of each type of atom must be on both sides
• Mixture


  Any combination of different types of elements and compounds that aren't chemically bonded together
• Separating a mixture


  1. Filtration (for large insoluble particles)

  2. Crystallization (evaporate solvent to leave solute)

  3. Distillation (heat solution, cool gas to condense liquid)
• Physical processes


  • No new substances are being made
• States of matter


  • Solid (particles vibrate around fixed positions)
  • Liquid (particles free to move past each other)
  • Gas (particles far apart, move randomly)
• Gases can be compressed, solids and liquids cannot
• Melting and evaporation


  Require energy (usually heat) to overcome electrostatic forces of attraction between particles
• Melting and evaporation are physical changes, not chemical reactions (no chemical bonds are broken)
• Atomic models


  • JJ Thompson: plum pudding model (positive charge with electrons)
  • Rutherford: nucleus with electrons orbiting relatively far away
  • Bohr: electrons in shells/orbitals
  • Chadwick: nucleus contains protons and neutrons
• Protons, electrons, neutrons


  • Protons: positive charge, mass 1
  • Electrons: negative charge, mass 0
  • Neutrons: no charge, mass 1
• Atomic number


  Number of protons in the nucleus
• Mass number


  Number of protons and neutrons in the nucleus
• Isotopes


  Atoms of the same element with different numbers of neutrons
• Relative atomic mass (RAM)

  Average mass of all isotopes of an element
• Development of the periodic table

  1. Ordered by atomic weight

  2. Grouped by properties (Mendeleev)

  3. Gaps predicted and later filled
• Electron configuration


  Arrangement of electrons in shells/orbitals around the nucleus
• Periodic table sections


  • Metals (left of staircase)
  • Non-metals (right of staircase)
  • Transition metals
• Group


  Column in the periodic table, indicates number of outer shell electrons
• Group names


  • Group 1: Alkali metals
  • Group 7: Halogens
  • Group 0: Noble gases
• Alkali metals


  • Have 1 electron in outer shell, readily donate it
  • Reactivity increases down the group
• Halogens


  • Have 7 electrons in outer shell, readily accept 1 more
  • Reactivity decreases down the group
  • Boiling points increase down the group
• Noble gases


  • Have full outer shells, very unreactive
• Ion


  Atom that has gained or lost electrons, no longer neutral
• Metallic bonding


  Atoms form a lattice with delocalized electrons around them
• Metals


  • Good conductors of electricity and heat
• Ionic bonding


  Metal atoms donate electrons to non-metal atoms to gain full outer shells
• Drawing ionic compounds


  1. Use dot and cross diagrams

  2. Brackets and charge for ions

  3. Formula must have overall charge of 0
• Ionic compounds


  • Consist of repeating units of ions in a lattice structure
  • Have high melting/boiling points
  • Can conduct electricity when molten or in solution
• Molecular ions


  Consist of atoms covalently bonded, but have an overall charge
• Covalent bonding


  Non-metal atoms share electrons to gain full outer shells
• Simple covalent molecules


  • Cl2, N2, H2O, CH4