structure and bonding

• Solids


  • Extremely hard to compress
  • Fixed shape, cannot flow
• Particles in solids


  Packed together in a regular pattern with almost no spaces between them
• Liquids


  • Extremely hard to compress
  • Take the shape of their container, can flow
• Particles in liquids


  Close together with not many spaces, can move
• Gases


  • Extremely easy to compress
  • Spread out and fill the space of their container
• Particles in gases


  Widely spaced, move quickly and randomly
• Melting


  1. Heating a solid to change it to a liquid

  2. Occurs at the melting point
• Particles in a liquid

  Have more kinetic energy than particles in a solid
• Stronger forces of attraction between particles

  Higher melting point
• Solids with different melting points

  • Wax candle (relatively low)
  • Sodium chloride (very high)
• Freezing


  1. Cooling a liquid to change it to a solid

  2. Occurs at the melting point
• Boiling


  1. Heating a liquid to change it to a gas

  2. Occurs at the boiling point
• Stronger forces of attraction between particles

  Higher boiling point
• Condensing


  1. Cooling a gas to change it to a liquid

  2. Occurs at the boiling point
• Limitations of simple particle model

  • Assumes particles are solid spheres (not true)
  • Assumes no forces between particles (not true)
• Electrons

  Exist in energy levels or shells
• Maximum electrons in energy levels

  • First energy level: 2
  • Second energy level: 8
  • Third energy level: 8
• Noble gases (group 0)

  • Have a full outer energy level
  • Are stable
  • Are unreactive
• Ionic bonding


  Occurs when a metal reacts with a non-metal
• During ionic bonding, group 1 metals lose 1 electron to form +1 ions, and group 7 non-metals gain 1 electron to form -1 ions
• Covalent bonding


  Bonding that occurs when non-metal atoms share electrons
• Covalent bond


  • A strong bond formed by shared pair of electrons
• Covalent bonding


  Shared pair of electrons between non-metal elements
• Covalent bond


  • Strong bond
• Covalent bonding


  1. Overlapping outer energy levels

  2. Sharing electrons

  3. Achieving full outer energy levels
• Water (H2O)

  Molecule contains 2 hydrogen atoms and 1 oxygen atom
• Dot and cross diagrams and stick diagrams can be used to represent covalent bonding
• Covalent bonding


  Shared pair of electrons between non-metal elements
• Covalent bond


  • Strong bond
• Covalent bonding


  1. Overlapping outer energy levels

  2. Sharing electrons

  3. Achieving full outer energy levels
• Water (H2O)


  Molecule contains 2 hydrogen atoms and 1 oxygen atom
• Dot and cross diagrams and stick diagrams can be used to represent covalent bonding
• Covalent bonding


  Sharing of electrons between atoms
• Covalent bonding


  1. Overlapping of outer energy levels

  2. Sharing of electron pairs
• Single covalent bond


  • Shared pair of electrons
• Double covalent bond


  • Two shared pairs of electrons
• Triple covalent bond


  • Three shared pairs of electrons
• Carbon dioxide (CO2)


  • Carbon forms double covalent bonds with each oxygen atom
• Giant covalent substances


  Contain millions of covalent bonds
• Giant covalent substances are always solids at room temperature