Chemistry Paper 1

• Substances are made of atoms, which are represented in the periodic table by symbols
• Compound


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


  A representation of a chemical reaction using words
• Chemical equation


  A representation of a chemical reaction using symbols
• Atoms are not created or destroyed in a chemical reaction, so the number of each type of atom must be the same on both sides of the equation</b>
• Balancing a chemical equation

  Start with atoms only in compounds, then balance other atoms by putting numbers in front of elements or compounds
• Mixture


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


  • Air
  • Salt water
• Solution


  A mixture of a solute (dissolved substance) and a solvent
• Separation techniques


  1. Filtration

  2. Crystallization

  3. Distillation
• Physical processes


  • No new substances are being made
• States of matter


  • Solid
  • Liquid
  • Gas
• Melting and evaporation are physical changes, not chemical reactions
• Discovered atoms are made of positive and negative charges


  JJ Thompson
• Discovered the positive charge is in a small nucleus, with electrons orbiting relatively far away


  Ernest Rutherford
• Discovered electrons exist in shells or orbitals

  Niels Bohr
• Discovered the nucleus contains neutral charges called neutrons


  James Chadwick
• Atomic number


  The number of protons in the nucleus
• Mass number


  The total number of protons and neutrons in the nucleus
• Isotopes


  Atoms of the same element with different numbers of neutrons
• Relative abundance


  The percentage of each isotope in a sample
• The periodic table was originally ordered by atomic weight, then later by atomic number and properties
• Electron configuration


  The arrangement of electrons in an atom's shells or orbitals
• Sections of the periodic table

  • Metals
  • Non-metals
• Group


  The column an atom is in on the periodic table, indicating the number of electrons in its outer shell
• Groups


  • Group 1 (alkali metals)
  • Group 7 (halogens)
  • Group 0 (noble gases)
• Ion


  An atom that has gained or lost electrons, giving it an overall positive or negative charge
• Transition metals


  Metals that can form ions with different charges
• Metallic bonding


  Bonding in metals where a lattice of positive ions is surrounded by delocalized electrons
• Ionic bonding


  Bonding between a metal and a non-metal, where the metal donates electrons to the non-metal
• Covalent bonding


  Bonding between non-metals, where they share electrons to fill their outer shells
• Molecular ion


  An ion formed from a group of atoms bonded together
• Salt


  Any ionic compound, not just sodium chloride
• Simple molecular/covalent structures


  Individual molecules that can mix together, with relatively low boiling points
• Giant covalent structures


  Structures where atoms are all covalently bonded in a continuous network, like diamond and graphite
• Allotropes


  Different structural forms of the same element, like diamond and graphite
• Nanoparticles


  Particles between 100-2500 nm in size, with a high surface area to volume ratio
• Total mass is conserved in a chemical reaction