3.7.3: periodic trend in bonding + structure Flashcards
what state are metals in at room temperature and what’s the exception?
solids
apart from mecury
what is metallic bonding?
the force of attraction/strong electrostatic attraction between cations and delocalised electrons within a metal
describe a solid metal structure/giant metallic lattice
each atom has donated its negative outer-shell electrons to a shared pool of electrons which are delocalised (spread out) throughout the structure
the cations left behind consist of the nucleus and inner electron shells which are in a fixed position and maintains the structure/shape of the metal
the delocalised electrons are mobile and able to move throughout the structure
what is the one constant property that all metals have?
they can conduct electricity
what are properties of giant metallic lattices?
high mp/bp because large amounts of energy are needed to overcome the strong electrostatic attraction between cations and delocalised electrons (relative as it depends on the strength of the metallic bond)
high electrical conductivity as they conduct in both solid and liquid states
don’t dissolve in water
what’s a giant covalent bond?
billions of atoms held together by a network of strong covalent bonds
what are properties of giant covalent lattices?
relatively high mp/bp because of the strong covalent bonds that require a large amount of energy to break
don’t conduct electricity (except graphene and graphite) because all the outer electrons are bonded and unavailable for conducting electricity
insoluble in almost all solvents because the covalent bonds are too strong to break
what are the trends in melting points across the period?
it increases from group 1-4 then there’s a sharp decrease in melting point which marks the change from giant to simple molecular structures
(giant structures have strong forces to overcome, simple structures have weak forces)
