structure-3

giant ionic lattice

physical properties of ionic compounds

• high melting and boiling points (takes a lot of energy to break the ionic bonds)

• soluble in water (aqueous solutions)

• don’t conduct electricity in solid form (ions held tightly and cannot move to carry the charge)

• conduct electricity when molten or aq( ions can now move)

what structures can covalently bonded substances have

• molecular covalent

• giant covalent

what is between covalent molecules

• weak intermolecular forces (van der Waal’s forces)

properties of molecular covalent molecules

• low melting and boiling points (little energy need to break the VDW forces) solid at room temperature

• do not conduct electricity (no charged particles to move)

• insoluble in water

molecular covalent substance

allotrope definition

alternative forms of the same element in the same physical state

diamond

giant covalent molecule (macromolecule)

diamond facts

• hardest know substances

• high melting point

• poor conductor of heat and electricity (no delocalised electrons to move)

graphite

graphite facts

• layered structure

• lubricant

• high melting point

• good conductor of heat and electricity (1 electron per carbon atom is not involved in bonding)

• soft and flaky (layers slide over one another)

graphene

graphene facts

• graphene is 1 single atom thick of graphite

• good conductor of heat and electricity

• used in batteries and solar cells

what is the structure of metals

giant metallic lattice

properties of metals

• good conductors (delocalised electrons move)

• malleable and ductile (one layer of met ions can slide over another layer without disrupting the bond)

• usually high melting and boiling points (forces of attraction is very strong)

alloy

alloy definition

a mixture of 2 or more elements at least one of which is a metal- has metallic properties

metallic bonding definition

the attraction between delocalised electrons and positive ions in a regular lattice

what is a nanoparticle

nanoparticles use structures that are 1-100 nm and contain a few hundred atoms

nanoparticle size

1×10(-9) m

nanoparticle advantages in suncream

• don’t leave a white residue

• better skin coverage

• more effective protection

risks of nanoparticles

• could be absorbed through the skin

• breathing then in mag cause inflammation of the lungs

• may be absorbed into the bloodstream

• we don’t know the long term effects