Metals Flashcards
Main group metals
metals in s and p block
transition metals
in d block
generally have unfilled d sub shell
Ores
Metals combined with non metals
Mineral
Naturally occurring solid substance with a definite chemical composition, structure and properties.
Metals bonding and ions
Metals are larger than non metals in the same period because of their lower core charge
Ionisation energy of metals is lower than that of non metals
Therefore metals can achieve greater stability by releasing one or more of their valence electrons into a common pool of electrons within the lattice
structure of metals
regular 3d lattice of cations
ions occupy fixed positions in a closely packed lattice
delocalised electrons which come from the valence shell are free to move throughout the lattice
localised electrons, electrons in the inner shells, are not free to move
How are ions held in metallic lattice
Ions are held by their attraction to delocalised electrons which extends throughout the lattice and is called metallic bonding.
Reason for metal structure
Solid where there is a lattice of metal cations and sea of delocalised electrons must be more stable than solid made up of seperate metal atoms
Properties of metals
good conductors of electricity and heat lustrous malleable and ductile high melting and boiling temp generally dense
Metals are good conductors of electricity
delocalised electrons are free to move
Metals are good conductors of heat
delocalised electrons bump into each other and ions and transfer energy
When metal is heated, particles get more energy and vibrate more rapidly
delocalised electrons transmit this energy rapidly throughout the lattice
Metals are lustrous
Delocalised electrons reflect light and appear shiny
Metals are malleable and ductile
When beaten into sheets or drawn into wires, layers of the positive ions are forced across each other
delocalised electrons move so that they still surround positive ions
electrostatic forces may change but still operate
prevent the ions from aligning and repelling when an external force is applied
Metals tend to have high melting and boiling temperatures
Attraction forces between the positive ions and delocalised electrons in the metal lattice are very strong
Metals are generally dense
Ions in a metal lattice are closely packed
Density depends on the mass of the ions, their radius and the way in which they are packed in the lattice
Transition metal properties
Compared to main group metals:
harded
higher densities
higher melting points
(atoms of transition metals are smaller because of higher core charge which allows them to pack together more tightly with stronger bonds)
Compounds (oxides, chlorides etc) display colours
Strong magnetic properties
Transition metal compounds display colours
Electrons absorb light of particular wavelength and move to higher energy levels.
Absorbance of light with some wavelengths and transmission of light of other wavelengths results in the compound appearing coloured
Reactivity of metals
Most reactive metals have lowest IE
Reactivity of metal and Ionisation energy are inversely proportional
Metals tend to be more reactive with
acids than water
Transition metal reactivity
usually less reactive than the main group metals
Metal + h2o->
metal OH- + H2 (g)
Metal + oxygen (o2) ->
metal oxide (s)
2K(s) + 2HCl (aq) ->
2KCl (aq) +H2 (g)
Alloys
Metals (usually Fe because of high abundance) are mixed with small amounts of another substance, usually a metal or carbon
The substances are melted, mixed and then allowed to cool
alloy has no chemical formula because it is not a substance and not chemically combined
Alloy properties compared to pure metals
harder, less malleable and lower melting point
poor electrical conductors
Alloys harder, less malleable and lower melting point
atoms of different size dont pack in same way as the main metal and do not allow lattice to shift or bend. disruption of the regular metallic lattice also accounts for these properties
Alloys poor electrical conductors
Delocalised electrons have restricted movement due to the close packing of different sized particles in the lattice
Substitutional alloy
made of elements that have similar chemical properties and atoms of similar size to main metal (must be another metallic cation)
all metal cations are attracted to sea of delocalised electrons so lattice is strongly bonded
Interstitial cation
small proportion of an element with atoms of small atomic radius are added to a metal (usually a non-metal like carbon)
Crystal
Region in a solid where the particles are arranged in a regular and continuous way
Crystals and metals
metal behaviour depends on size and arrangement of crystals
Smaller crystals
Result in a harder, but more brittle metal
less free movement of layers of cation over each other
Heat treatment
When heated, the individual crystals merge and when the metal is allowed to cool, the crystals reform
rate of cooling determines how large the new crystal will be
Quenching
Faster cooling
leads to smaller crystals
Annealing
Slower cooling
allows more time for crystals to grow larger
metallic nano materials
have very different properties when compared to a bulk sample of same metal because they have a very high surface area to volume ratio
