Giant covalent substances Flashcards
Key concepts in chemistry
Buckyballs
Definition
Molecules comprising carbon atoms joined together to form spherical or nearly spherical hollow structures.
Charge
definition
Property of matter that causes a force when near another charge. Charge comes in two forms, positive and negative. For example, a negative charge causes a repulsive force on a neighbouring negative charge.
Covalent network
Definition
Giant regular arrangement of atoms, with a repeating pattern, held together by covalent bonds.
delocalised
Definition
Electrons that are not associated with a particular atom, eg in a metal, outer electrons can be free to move through the solid.
Diamond
definition
A form (allotrope) of pure carbon in which all the atoms are bonded to four others in a giant tetrahedral network structure which is very strong. Diamond is a the hardest known natural substance, has a very high melting point and does not conduct electricity.
Electrode
definition
A conductor used to establish electrical contact with a circuit. The electrode attached to the negative terminal of a battery is called a negative electrode, or cathode. The electrode attached to the positive terminal of a battery is the positive electrode, or anode.
fullerenes
Definition
Molecules of carbon with hollow shapes. Their structures are based on hexagonal rings of carbon atoms.
graphene
Definition
A form of carbon consisting of a single layer of carbon atoms joined together in hexagonal rings.
graphite
Definition
A form of pure carbon in which all the atoms are bonded to three others in giant sheets which can slide over each other.
Intermolecular forces
Definition
Weak attractive forces between molecules. When a simple molecular substance melts or boils, it is the intermolecular forces that are broken (not the covalent bonds in each molecule).
Lattice
definition
A regular grid-like arrangement of atoms in a material.
Lubricant
definition
A lubricant is anything which reduces the friction between two surfaces.
molecular
definition
Refers to a substance made up of molecules, so it contains small groups of atoms, of a set size, held together by covalent bonds.
Nanotubes
definition
Long cylindrical molecules made from carbon atoms joined together by covalent bonds.
Polymer
Definition
A large molecule formed from many identical smaller molecules known as monomers.
