Bonding, structure, and the properties of matter

• The three types of strong chemical bonds are:

  • ionic
  • covalent
  • metallic
• The particles in ionic bonding are oppositely charged ions
• The particles in covalent bonds are atoms which share pairs of electrons
• The particles in metallic bonding are atoms which share delocalised electrons
• Ionic bonding happens in compounds formed when metals combine with non-metals
• Covalent bonding happens in non-metallic elements and non-metal compounds
• Metallic bonding happens in metallic elements and alloys
• Chemical bonding is the result of electrostatic interactions between positively and negatively charged ions
• Ionic bonding is the transfer of electrons between a metal and a non metal
• In ionic bonding, the metal atoms lose electrons to become positively charged ions
• In ionic bonding, the non-metal atoms gain electrons to become negatively charged ions
• Covalent bonding is the sharing of electrons between two non metalswhich have strong bonds between atoms
• An ionic compound is a giant structure of ions
• Ionic compounds are held together by strong electrostatic forces of attraction between oppositely charged ions
• Sodium chloride is a giant ionic lattice
• Polymers are covalently bonded substances with very large molecules
• Diamond and sillicon dioxide are both covalent bonded substances with giant covalent structures
• Metals consist of giant structures of atoms arranged in a regular pattern
• Electrons in the outer shell of metal atoms are delocalised, so they can move freely around the metal lattice
• Solid, liquid and gas are the three states of matter
• Melting and freezing take place at the melting point
• Boiling and condensing take place at the boiling point
• The amount of energy needed to change state depends on the strength of the forces between the particles of the substance
• If the forces between particles are strong, the melting and boiling points are higher
• The particle theory states that:

  • when a solid is heated, its particles gain more energy
  • which makes the particles move more
  • which weakens the forces holding the soild together
  • therefore, particles require heat to change state
• ionic compounds have high melting and boiling points because they have a lot of energy to break the bonds
• When ionic compounds are melted or dissolved in water, they conduct electricity because ions are free to move and so charge will be able to flow
• Gases and liquids have low melting and boiling points
• Gases and liquids have intermolecular forces between molecules
• Intermolecular forces are weaker forces of attraction between molecules
• Intermolecular forces increase with the size of the molecules, so larger molecules will have higher melting and boiling points
• Polymers have large molecules
• Atoms in polymer molecules are linked to other atoms by strong covalent bonds
• Polymers are solids at room temperature because the intermolecular forces are strong
• Subtances with giant covalent structures are solids with very high boiling and melting points
• Examples of giant covalent structures include:

  • diamond
  • graphite
  • sillicon dioxide
• Most metals have high melting and boiling points because metals have giant structures of atoms with strong metallic bonding
• In pure metals, atoms are arranged in layers

  this allows metals to be bent
• Pure metals are too soft, so they are mixed with other metals to make alloys which are hard
• Alloys are harder than pure metals because alloys are made up of atoms of different sizes

  so the layers dont slide over easily