what are the properties of covalent substance?
low melting points
not soluble in water
poor conductors of electricity
why do covalent compounds have low melting points
there are only strong forces holding the atom in the molecules, and very weak bonds hllding the molecules to one another
why are covalent substance poor conductors?
the electrons cannot properly ove around the atoms as the are held in place , attched to tother atoms
what is the stucture of a polymer?
a polymer is like a large molecule consisting of a repeating patter of monomers(simple molecules)which are molecularly bonded to each other in a long chain where by the carbon atoms are covalently bonded to each other
what are 3 common allotropes of carbon
diamond, buckminster fullerenes, graphite
what are the main difference between covalent, simple molecules and giant covalent structures
- a lot bigger
- very high melting points
- some can conduct electricity
- some form very large molecules(e.g. fullerenes), some can be infinitly large(e.g. nano tubes)
what is the structure and properties of diamond
diamond is an allotrope of carbon, in which each carbon atom is covalently bonded to 4 other carbon atoms.
it has a high melting point, doesnt conduct electricity, transparent and very hard
what is the structure and properties of fullerenes
fullerenes are giant molecules consisting of 28, 32, 50, 60, 70, 240 etc, carbon atoms, in a spherical shape with man sides in the shape of a regular pentagon or hexagon.
forms a black solid which is soluble in various solvents, cant conduct eectricity on its own, has delocated electrons which move around but are confined to each molecule
what is the structure and properties of graphite
consists of layers of sheets of carbond arranged in hexagons, with each carbon atom bonded to 3 others, each atom has a delocalised electron which moves freely around its layer.
high melting point, insoluble in water, conducts electricity because the delocalised electrons can carry charge acros the substance
what is the structure and properties of graphene
arranged i9n a single layer sheet of carbon atoms bonded to 3 others, in a regular hexagon shape, each atom has a delocalised electron
it has a high melting point and is very strong, conducts electricity well because of its delocalised electrons
what is the structure of metals
metal ions are arranged in a regular patter within a sea of delocalised electrons, which these positively charged metal ion are attracted to
why are metals malleable
due to the regular arrangement of atoms, layers are able to slide over each other to move out of the way and easily change shape instead of shattering
why do metals conduct electrons
the sea of delocalised electrons are able to move freely around the metal ions and can carry charge throuh the substance
what are the typical properties of metals
high melting point
good conductor of heat and electricity
what are the typical properties of non-metals
low melting points
poor conductors of electricity and heat