Atoms, Elements, and Compounds

• Subatomic Particles

  • Electrons
  • Protons
  • Neutrons
• Atomic Mass Number


  Number of protons + number of neutrons
• Atomic Number


  Number of protons
• How to find the amount of neutrons in an atom

  Atomic mass number - Atomic number = Number of neutrons
• Categories that things on Earth can be sorted into

  • Matter
  • Energy
• Examples of Matter and Energy

  • Fire (Energy)
  • Soil (Matter)
• There is always the same amount of protons and electrons in a neutral atom
• Electrons


  Negative charge, orbiting the nucleus in the outer-shell
• Protons


  Positive charge, inside the nucleus
• Neutrons


  Neutral charge, inside the nucleus
• Element


  A substance that is made of only one type of atom
• Monatomic substance


  One single type of atom
• Molecule


  Small groups of chemically bonded atoms
• Lattice


  Large groups of atoms
• Rules for drawing an atom

  1. Write the number of protons and neutrons in the nucleus

  2. Put electrons in outer shells/rings
• Electron shells/rings


  • 1st ring is only 2 electrons
  • 2nd ring is 8 electrons
  • 3rd ring is 8 electrons
  • Each new ring after the 1st ring is 8 electrons
• Valence


  The outermost electrons in an atom. e.g. All the electrons in the outermost shell. These valences are the subatomic Particles that react with other things around them.
• Group 1 - 1 valence
• Group 2 - 2 valence
• group 13, 14, 15, 16, 17, 18 - 3, 4, 5, 6, 7, 8
• Group 1 has elements that react easily and Group 8 has elements are stable so they are hard to react.
• Element


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


  A substance that is made up of more that one type of atom, they are chemically bonded
• Mixture


  A combination of two or more elements or compounds which have not reacted to bond together. Mixtures are not chemically bonded. The only thing that is chemically bonded are the compounds.
• Ions

  Atoms give their valences away or take valences off of other atoms
• Giving or taking valences


  Depends on which is easier
• Cations


  Positive charge (more protons than electrons)
• Anions


  Negative charge (more electrons than protons)
• Ionic Compound


  A metal (Cation - positive charge) + non-metal (Anion - negative charge)
• Elements for Ionic Compounds are chosen because it balances out the charges - positive and negative
• Ratios in chemistry


  The ratio between Cations and Anions in chemical formulas/compounds
• Covalent Bonding


  When a non-metal bonds to another non-metal atom to make both atoms stable. They don't give or take away electrons, they share them.
• Physical Changes


  When no new substances are formed. The old substance may have changed into a new form but it's not a new substance. The attractions become weaker or stronger but bonds aren't changed. Physical change is reversible.
• Chemical Changes


  When a new substance is formed. There has been a chemical reaction. Bonds are broken or formed and chemical changes are very hard to reverse.
• Balancing equations - Accounting Method

  1. Count the number of each type of atom on either side

  2. If more atoms are needed to make both number of atoms the same, put a big number in front of the chemical symbol

  3. Don't ever put the tiny number on the bottom on the chemical symbol because it is too complicated

  4. When balancing out equations, always do C(carbon), H(hydrogen) and O(oxygen) last in that specific order
• Malleable


  Bends without breaking
• Brittle


  Breaks easily when it is bent
• Sonorous


  Metal makes a sound when hit against a solid surface
• Lustre


  Metal that is shiny
• Electrical Conductivity


  Metal that conducts electricity