First-row d-block elements Use sections 8 and 9 in your IB data booklet to compare the trend and the extent of the trend for atomic radius, first ionization energy and electronegativity between the 8 elements in period 3 and the 10 elements in the first row in the d-block. What characteristic properties do the first row d-block elements have? Compare and contrast their properties with potassium and calcium. What are iron, nickel, manganese used for? Use an interactive periodic table.

First-row d-block elements Variable oxidation states e.g. Fe2+ and Fe3+, Cu+ and Cu2+. Form complex ions e.g. [Cu(NH3)4]2+ Form coloured compounds Can act as catalysts Show magnetic properties Why?

Electron configuration

Common oxidation states Sc Ti V CR Mn Fe Co Ni Cu +1 +2 +3 +4 +5 +6 +7

Successive ionization energies Compare the successive ionization energies of aluminium and vanadium I.E. kJ mol -1 Al V 1 +578 +651 2 +1820 +1370 3 +2740 +2870 4 +11600 +4600 5 +14800 +6280

Transition metals/elements A transition element is a d-block element that has an atom with a partially filled d-sub-level or that forms at least one stable cation that has a partially filled d-sub-level. As a result zinc is not considered a transition metal.

Complex ions

which can be shared with incomplete d-subshell of TM TRANSITION METAL COMPLEXES = central METAL ION (or atom) with a FIXED number of MOLECULES or ANIONS (called LIGANDS) bonded to it by DATIVE (COORDINATE) bonds. “COMPLEX”  have no net charge eg Ni(CO)4 “COMPLEX ION”  have a net charge eg [CuCl4] 2- = anionic (-ve) complex [Ni(H2O)6] 2+ = cationic (+ve) complex Ligands have LONE PAIR(S) which can be shared with incomplete d-subshell of TM to form the coordinate bond(s), and hence the complex eg [CuCl4] 2- ligand is :Cl- [Ni(H2O)6] 2+ ligand is H2O:

Complex ions monodentate and polydentate ligands

[Fe(H2O)6] metal ion = Fe2+ [Fe(H2O)5OH] metal ion = Fe3+ Determine the charge on each complex – where the charge of the ion is not mentioned also determine that [Fe(H2O)6] metal ion = Fe2+ [Fe(H2O)5OH] metal ion = Fe3+ [CuCl4] metal ion = Cu2+ [Mn(H2O)6] SO4 [Co(NH3)6] (NO3)3 [NH4]2 [Fe(H2O)6] (SO4)2

Coloured compounds

Coloured complex ions

Colour wheel

Splitting d-sublevel in Cu2+

Coloured ions: factors affecting the colour

Colour complex ions

Challenge Study the graphs and use them together with the colour wheel in your textbook to identify the colour shown by each complex ion. Use the information below about each ligand to identify which graph shows the absorption of ligand A and B. Justify your answer: Ligand A: more electronegative; holds electrons more closely to nucleus Ligand B: less electronegative

Nature of ligand

Factors affecting colour or factors affecting split or Δ􏰈E oxidation state of metal ion (i.e. number of 3d electrons, the more electrons the greater the repulsion) nature of ligand (different repulsion/greater split e.g. by less electronegative atoms or ligands with greater charge density ) identity of metal ion/nuclear charge (attraction between nucleus and non-bonding pairs) coordination number/number of ligands shape of the complex ion

Spectrochemical series See data booklet The further up the series the greater the splitting in d-orbitals

Paramagnetic particles Attracted weakly to a magnetic field. Atoms or ions that contain unpaired d electrons behave like small magnets. Because of their spin electrons create a magnetic field that can align itself to an external electric or magnetic field when exposed to it; unpaired electrons can do this because they can spin in any direction – they create a net magnetic moment. The greater the number of unpaired electrons the more paramagnetic the material. The alignment is only temporary so they are only magnetic for a short period of time. Examples of paramagnetic materials in the first row d-block: atoms: all apart from Zn. ions e.g. in compounds and complexes: e.g. Mg2+ has 5 unpaired electrons, Co2+ (3 unpaired electrons), Ni2+ (2 unpaired electrons), Fe2+ ( unpaired electrons).

Diamagnetic particles Weakly repelled by external magnet Have paired d-electrons and therefore create a magnetic field opposed or not aligned to an external field. The paired electrons cancel out each other’s magnetic field so there is no net magnetic moment in the atom or ion. Examples of diamagnetic materials: Zn and Zn2+.

VARIABLE OXIDATION STATES OF IRON REDUCTION Brown Fe3+ Fe2+ Pale green OXIDATION Reduction carried using excess granulated Zn in dilute sulphuric acid 2Fe3+ + Zn  2Fe2+ + Zn2+ Excess zinc can be filtered off after reduction. Oxidation can be carried out using excess H2O2(aq) in dilute NaOH solution 2Fe2+ + H2O2  2Fe3+ + 2OH- Iron(III) will form Fe(OH)3(s) in alkali Converted to Fe3+(aq) by adding dil. acid Fe(OH)3(s) + 3H+(aq)  Fe3+(aq) + 3H2O(l)

OXIDATION STATES OF CHROMIUM +6 +3 +2 CrO42- Cr2O72- = chromate(VI) = dichromate(VI) YELLOW ORANGE [Cr(OH)6]3- [Cr(H2O)5(OH)]2+ [Cr(H2O)6]3+ = hexahydroxo- chromium(III) ion = pentaaquohydoxo- chromium(III) ion = hexaaquo- chromium(III) ion DARK GREEN GREEN RUBY [Cr(H2O)6]2+ Exist in equilibrium in aqueous solution. GREEN predominates. Ruby in crystal or at very low pH. = hexaaquo- chromium(II) ion BLUE

OXIDATION STATES OF COBALT + Excess NH3 +2 +3 [Co(H2O)6]2+(aq) [Co(NH3)6]2+(aq) PINK / RED STRAW YELLOW UNSTABLE! OXIDATION by heat with H2O2 in NaOH(aq) OXIDATION Quickly by H2O2 in NH3(aq) or slowly by O2 from air Co(OH)3(s) [Co(NH3)6]3+(aq) DARK BROWN DARK RED STABLE

OXIDATION STATES OF COPPER +2 +1 [Cu(H2O)6]2+ [Cu(H2O)6]2+ + Cu BLUE BLUE REDUCTION by heating with copper in conc. HCl DISPROPO RTIONATION by adding dil. H2SO4 [CuCl2]- CuCl(s) COLOURLESS WHITE PRECIPITATION by adding water Note: Copper(I) oxide, Cu2O is the brick-red ppt. formed during a positive Fehling’s test. CuCl(s) WHITE

Match up correct explanation Typical property Match up correct explanation A. Form coloured compounds 1. Variable oxidation states and empty orbitals B. Can acts as a catalyst 2. Transition metal ions have high charge density C. Variable oxidation states 3. Partially filled split 3d sublevel and d-to-d transitions D. Can form complexes or complex ions with negative ions and molecules 4. 3d sublevel to be filled closer to nucleus than 4s sublevel. Increased shielding offsets increased nuclear charge. Similar atomic radii E. Magnetic properties 5. Small differences in successive ionization energies F. Similar first ionization energies 6. Unpaired 3 d electrons