New Technology Noadswood Science, 2016

New Technology To know how new technology can be used Tuesday, April 24, 2018 New Technology To know how new technology can be used

Precise Learning In diamond, each carbon atom forms four covalent bonds with other carbon atoms in a giant covalent structure, so diamond is very hard, has a very high melting point and does not conduct electricity. Students should be able to explain the properties of diamond in terms of its structure and bonding. In graphite, each carbon atom forms three covalent bonds with three other carbon atoms, forming layers of hexagonal rings which have no covalent bonds between the layers. In graphite, one electron from each carbon atom is delocalised. Students should be able to explain the properties of graphite in terms of its structure and bonding. Students should know that graphite is similar to metals in that it has delocalised electrons. Graphene is a single layer of graphite and has properties that make it useful in electronics and composites. Students should be able to explain the properties of graphene in terms of its structure and bonding. Fullerenes are molecules of carbon atoms with hollow shapes. The structure of fullerenes is based on hexagonal rings of carbon atoms but they may also contain rings with five or seven carbon atoms. The first fullerene to be discovered was Buckminsterfullerene (C60) which has a spherical shape. Carbon nanotubes are cylindrical fullerenes with very high length to diameter ratios. Their properties make them useful for nanotechnology, electronics and materials. Students should be able to: recognise graphene and fullerenes from diagrams and descriptions of their bonding and structure give examples of the uses of fullerenes, including carbon nanotubes.

Diamond Diamond is a form of carbon in which each carbon atom is joined to four other carbon atoms, forming a giant covalent structure All the electrons in the outer shell of the carbon atom (2.4) are used in covalent bonds – this affects diamond’s properties As a result, diamond is very hard and has a high melting point and it does not conduct electricity (the hardest naturally occurring substance on Earth)

Graphite Graphite is a form of carbon in which the carbon atoms form layers – these layers can slide over each other, so graphite is much softer than diamond This forms rings of six atoms, creating a giant structure containing many layers – these layers are held together by weak forces of attraction Only three of the four electrons in the outer shell of the carbon atom (2.4) are used in covalent bonds – graphite conducts electricity and it is also used in pencils, and as a lubricant

Fullerenes Buckminsterfullerene is yet another allotrope of carbon – it is actually not a giant covalent structure, but a giant molecule Buckminsterfullerene contains 60 carbon atoms, each of which bonds with three others by forming two single bonds and one double bond – these atoms are arranged in 12 pentagons and 20 hexagons to form spheres, which are sometimes called ‘bucky balls’

Graphene Graphene is a sheet of carbon atoms joined together in hexagons – it is basically a single layer of graphite (the sheet is one atom thick, making a two-dimensional compound) The network of covalent bonds make graphene very strong – it is also incredibly light so it can be added to composite materials to improve their strength

Practice Questions Match the following properties with the correct substance Conducts electricity Melting point 3500oC Ammonia Does not conduct electricity Melting point 3500oC Graphite Does not conduct electricity Melting point -78oC Diamond

Answers Conducts electricity Melting point 3500oC Ammonia Does not conduct electricity Melting point 3500oC Graphite Does not conduct electricity Melting point -78oC Diamond