S2.3 Metallic Flashcards
what is a metallic bond?
the electrostatic attraction between a lattice of cations and a sea of delocalized electrons
why are metallic compounds malleable?
bc when a force is applied, the layers can slide and the attractive forces between the metal ions and electrons act in all directions so when the layers slide the metallic bonds are re-formed so lattice not broken and has changed shape
why are metallic compounds strong and hard?
due to the strong attractiveness of forces between the metal ions and delocalised electrons
why do metals have high mp and bp?
bc of the strong electrostatic forces of attraction between cations and delocalised electrons in the lattice which requires lots of energy to overcome
what are the factors that affect the strength of metallic bonds?
the charge on the metal ion(greater charge=stronger bonds), the radius of the metal ion(smaller radii=greater attraction on sea of delocalised electrons)
mp of metals across a period
as the no. of valence electrons increases the mp increases
m.p. of metals going down a group
the size of the cation increases which decreases the attraction between the outer electrons and metallic lattice so decreases
what is the definition of a transition metal?
an element with an incomplete d-subshell
why do transition metals have high m.ps?
ability to delocalise the d-electrons means transitions have a greater electron density, so electrostatic forces of attraction between the large + charge of the cations and sea of delocalised electrons are stronger so higher mp
why do transition metals have high electrical conductivity?
have lots of delocalised electrons, so more electrons can move when pd(potential diff) is applied so high electrical conductivitity
what is charge density?
the charge divided by the volume of the ion-higher charge density=attracts delocalised electrons more strongly
properties and uses of copper
good conductor of electricity, ductile, used in a close to pure form in electrical cabling, presence of impurities reduces electrical conductivity
properties and uses of aluminium
good conductor of electricity, ductile, relatively low density ideal for use in overhead power cables
why do transition metals have much higher m.p.s than alkali metals?
because of the delocalisation of d electrons-higher charges on ions and more delocalised electrons=stronger metallic bonding
trend in mps of transition metals across period
increase in charge on positive ions formed as the 2 s electrons and more d electrons are delocalised, ionic radius also decreases so stronger attraction between + ions and delocalised electrons so higher mp
