transition metals Flashcards
properties of d-block elements
- high MP/BP
- shiny
- conduct electricity + heat
what elements have special cases in electron configuration
- chromium and copper
- 3d fills before 4s so they both have 1 e- in 4s
- reason : stability
- half filled 3d5 and full 3d10 gives additional stability to chromium and copper
define transition elements
- d-block elements that form at least one ion with a partially filled d-orbital
- scandium and zinc are d-block but no t-metals
- Sc3+ forms empty d-orbital
- Zn2+ forms full d-orbital
properties of transition metals
- form compounds where the t-elements has a diff Ox. state
- form coloured compounds
- catalysts
transition metals as catalysts
- Haber process - iron catalyst
- contact process to form sulphur trioxide (SO3) from oxidation of sulphur dioxide - vanadium (V) oxide catalyst (V2O5).
Cu2+ with:
- NaOH
- excess NaOH
- blue solution to blue precipitate of Cu(OH)2
- no change bc ppt = insoluble
Fe2+ with:
- NaOH
- excess NaOH
- pale green solution to green ppt of Fe(OH)2 (brown when exposed to air Fe(OH)3)
- no change , ppt = insoluble
Fe3+ with:
- NaOH
- excess NaOH
- pale yellow sol to orange/brown ppt
- no change , ppt = insoluble
Mn2+ with :
- NaOH
- excess NaOH
- pale pink sol to light brown ppt (darkens on standing)
- no change , ppt = insoluble
Cr3+ with:
- NaOH
- excess NaOH
- green solution to grey/green precipitate
- in excess = dark green Cr(OH)6
Fe2+
- NH3
- excess NH3
- no reaction bc don’t dissolve
- pale green to green
Fe3+
- NH3
- excess NH3
- no reaction bc don’t dissolve
- pale yellow to orange/brown ppt
Mn2+
- NH3
- excess NH3
- no reaction bc don’t dissolve
- same as NaOH : pale pink to light brown
Cu2+
- NH3
- excess NH3
- blue to blue ppt
- ppt dissolves = deep blue solution of [Cu(NH3)4(H2O)2]2+
Cr3+
- NH3
- excess NH3
- green to grey/green gel ppt
- dissolves in excess to form purple sol of [Cr(NH3)6]3+
Zn2+ ion colour
- colourless
Al3+ ion colour
- colourless
ligand
- mol/ion
- bonds to metal ion
- forms coordinate bond
- donates a lone pair of e- into a vacant d-orbital
- H20 , :CN- , :NH3
complex ion
- central metal ion surrounded by ligands
monodentate ligand
bidentate ligand
- donates one pair of e- to central metal ion
- donates 2 lone pairs of e- to the central metal ion
when is a square planar complex formed
- t-metals with eight d-e- in d-sub shell
- Platinum(II) , palladium (II) and gold (III)
- bond angle 90
- cis-platin drug
stereoisomer
- same structural formula but a different arrangement of atoms in space.
what types of stereoisomerism can complex ions display
- cis-trans
- optical
structural formula for 1,2-diaminoethane
NH2CH2CH2NH2
cis platin as an anti-cancer drug
- during chemotherapy
- an anti-cancer drug
- colourless liquid
- drip into vein
- forms a platinum complex inside of cells
- binds onto DNA of cancerous cells
- prevents division
- trans molecule is ineffective
Cu2+ reaction with NH3
- [Cu(H20)6]2+ + 4NH3 = [Cu(NH3)4(H20)2]2+ + 4H20
- in ammonia = pale blue
- excess ammonia = dark blue
- 4 NH3 ligands replace 4H2O ligands
- 2 H2O left over
Cu2+ with HCL
- [Cu(H20)6]2+
- add conc HCl
- 6 H2O replaced by 4 chloride ligands
- pale blue to green intermediate to yellow
- ## [Cu(H2O)6]2+ + 4Cl- = [CuCl4]2- + 6H20
why do only 4 Cl- ligands bond with Cu
- chloride ligands are larger than water ligands
- fewer chloride can fit around central Cu2+ ion
Cr3+ with ammonia
- [Cr(H2O)6]3+ undergoes ligand substitution with excess NH3
- first, grey ppt of Cr(OH)3 formed
- Cr(OH)3 ppt dissolves in excess NH3 to form purple [Cr(NH3)6]3+
- [Cr(NH3)6]3+ = violet
