bonding

• COVALENT BONDING P1 - what is covalent bonding?

  atoms can share or transfer electrons to form strong chemical bonds. a covalent bond is when electrons are shared between non-metal atoms.
• COVALENT BONDING P1 - what is a giant covalent bond? what is an example? do they have a low or high melting and boiling point?

  many billions of atoms, each one with a strong covalent bond to a number of others. An example of a giant covalent structure is Dimond. they have a high melting and boiling point
• COVALENT BONDING P1 - what are small molecules? what is an example? do they have high or low melting and boiling points?

  Each molecule contains only a few atoms with strong covalent bonds between these atoms. Different molecules are held together by weak intermolecular forces. For example, water is made of small molecules. they have low melting and boiling points.
• COVALENT BONDING P1 - what are large molecules? what is an example? do they have high or low melting and boiling points?

  many repeating units joined by covalent bonds form a chain. Separate chains are held together by intermolecluar forces that are stronger than in small molecules. Polymers are examples of large molecules. melting and boiling points are low.
• COVALENT BONDING P1 - what is the structure of graphite?

  made only of carbon - each carbon atom bonds to three others, and forms hexagonal rings in layers. each carbon atom has one spare electron, which is delocalised.
• COVALENT BONDING P1 - how hard is graphite?

  the layers can slide over each other because they are not covalently bonded. graphite is therefore softer than Dimond.
• COVALENT BONDING P1 - what is the conductivity like in graphite?

  the delocalised electrons are free to move through graphite, so can carry charges and allow an electrical current to flow. yes it can conduct electricity.
• COVALENT BONDING P1 - can fullerenes conduct electricity?

  yes they can conduct electricity.
• COVALENT BONDING P1 - what are fullerenes used for?

  can be used in drug delivery and lubricants.
• COVALENT BONDING P1 - what was the first fullerene to be discovered?

  buckminsterfullerene - 60 carbon atoms.
• COVALENT BONDING P1 - what are nanotubes?

  they are carbon atoms that are arranged in cylindrical tubes. their high tensile strength makes them useful in electronics. they can conduct electricity.
• IONIC BONDING, METALLIC BONDING, AND STRUCTURE P1 - what is an ion?

  an atom that has lost or gained electrons.
• IONIC BONDING, METALLIC BONDING, AND STRUCTURE P1 - what is a giant ionic lattice?

  when metal atoms transfer electrons to non - metal atoms you end up with positive and negative ions. these are attracted to each other by the strong electrostatic force of attraction, this is called ionic bonding. the 3D structure that holds millions of these bonds are giant ionic lattices.
• IONIC BONDING, METALLIC BONDING, AND STRUCTURE P1 - what is ionic bonding?

  when metal atoms react with non-metal atoms they transfer electrons to the non-metal atom (instead of sharing them).
• IONIC BONDING, METALLIC BONDING, AND STRUCTURE P1 - how do positive ions form?

  metals atoms lose electrons to become positive ions.
• IONIC BONDING, METALLIC BONDING, AND STRUCTURE P1 - how do negative ions form?


  non-metal atoms gain electrons to become negative ions.
• IONIC BONDING, METALLIC BONDING, AND STRUCTURE P1 - what are the two ionic properties?

  they have high melting points because of the strong electrostatic force of attraction between oppositely charged ions. they don't conduct electricity because the ions are fixed in posisiton, however when melted or dissolved in water, ionic substances do conduct electricity because the ions are free to move.
• IONIC BONDING, METALLIC BONDING, AND STRUCTURE P1 - what is it called when the metals are free to move?

  delocalised.
• IONIC BONDING, METALLIC BONDING, AND STRUCTURE P1 - are metals malleable?

  pure metals are malleable because the layers can slide over each other.
• IONIC BONDING, METALLIC BONDING, AND STRUCTURE P1 - are metals conductive of electricity?

  metals are good conductors of electricity and of thermal energy because delocalised electrons are free to move through the whole structure.
• IONIC BONDING, METALLIC BONDING, AND STRUCTURE P1 - do metals have low or high melting points?

  metals have high melting and boiling points because the electrostatic force of attraction between metal ions and delocalised electrons is strong so lots of energy is needed to break it.
• IONIC BONDING, METALLIC BONDING, AND STRUCTURE P1 - what is an alloy?

  mixture of a metal with atoms of another element.
• IONIC BONDING, METALLIC BONDING, AND STRUCTURE P1 - describe the structure of a pure metal.

  layers of positive metal ions surrounded by delocalised electrons.
• IONIC BONDING, METALLIC BONDING, AND STRUCTURE P1 - explain why alloys are harder than pure metals.

  different sized atoms disturb the layers, preventing them from sliding over each other.
• IONIC BONDING, METALLIC BONDING, AND STRUCTURE P1 - describe the structure of a giant ionic lattice.

  regular structure of alternating positive and negative ions, held together by the electrostatic force of attraction.