Module 5: Chapter 24 (Transition Elements)

between Group 2 and Group 13

from Sc to Zn 3d sub-shell has the highest energy level

• all metals, form metallic bonds • good conductors of heat and electricity • high melting and boiling points

Cu, Ni, Zn and Ag are used in coins Fe is used to make steel used in construction and tool making Cu is used in water pipes and electrical wiring

[Ar]3d5 4s1 - half filled d-subshell

[Ar] 3d10 4s1 - fully filled d sub-shell

It is believed that the half-filled or fully filled d sub-shell gives additional stability to atoms of chromium and copper

4s empties before 3d orbitals when forming an ion (4s fills before 3d when forming an atom, first in first out)

d-block elements that form at least one ion with a partially filled d-orbital

both only form one ion without a partially filled d-orbital Sc3+ = 1s2 2s2 2p6 3s2 3p6 (empty d-orbitals) Zn2+ = 1s2 2s2 2p6 3s2 3p6 3d10 (full d-orbitals)

• they can form compounds in which the transition element has different oxidation states • they form coloured compounds • many transition elements and their compounds can act as catalysts

• each oxidation state has a characteristic colour • the number of oxidation states increases across the series to manganese and then decreases • a species containing a transition element in its highest oxidation state is often a strong oxidising agent (e.g. manganate (VII) ion MnO4^-)

• compounds and ions of transition metals are frequently coloured • e.g. potassium dichromate (VI) is orange and hydrated copper (II) sulfate is blue • solid compounds can be dissolved in water to produce coloured solutions • colour of a solution is linked to the partially filled d-orbitals of the transition metal ion

A catalyst is a substance that increases the rate of a chemical reaction without itself changing. It works by providing an alternative reaction pathway of lower activation energy.

• an iron catalyst used in the Haber Process to make ammonia • Vanadium (V) Oxide (V2O5) is used in the Contact Process (manufacture of sulfuric acid), catalyses the reaction of 2SO2 + O2 <=> 2SO3 • Nickel used in the hydrogenation of vegetable oils to make margarine

The catalyst is in a different state to the reactants

HOMOGENEOUS catalysts… - Reaction between iodide ions and peroxodisulfate ions is catalysed by Fe2+(aq) ions S2O8^2-(aq) + 2I-(aq) -> 2SO4^2-(aq) + I2(aq) - How Fe2+ catalyses reaction… Fe2+ reacts: S2O8^2- + Fe2+ -> 2SO4^2- + Fe3+ Fe2+ regenerated: Fe3+ + 2I- -> I2 + Fe2+ • Reaction of zinc metal with acids is catalysed by the presence of Cu2+(aq) ions

A region around a nucleus where there is a high probability of finding an electron - an orbital can hold up to 2 electrons with opposite spin

• sphere shape - one occurs in every principal energy level

• dumb-bell shaped • 3 orbitals in the z, y and x axis • 3 orbitals occur in energy levels except the first

A complex ion is formed when one or more molecules or negatively charged ions (ligands) bond to a central metal ion

A ligand is a molecule or ion that donates a pair of electrons to a central metal ion to form a coordinate bond or dative covalent bond

A shared pair of electrons in which the bonded pair has been provided by one of the bonding atoms only

The coordination number indicates the number of coordinate bonds attached to the central metal ion