transition metals Flashcards
define transition elements
a metal that can form one or more stable ions with a partially filled d-subshell
what d-block elements arent transition metals and why
scandium and zinc do not form stable ion with partially filled d-subshell
what is the electron configuration of chromium
[Ar] 4s1 3d5
this is due to both 4s and 3d being half full gives chromium more stability than a full 4s and partially full 3d
whats the electron configuraton of copper and why
[Ar] 4s0 3d10
more stable with full 3d-subshell and half full 4s
how does energy levels change once the 3d subshell gains its first electron
and what does this result in
- 4s become higher energy level than 3d
- as 4s becomes higher energy level than 3d this means that electrons are lost from the 4s subshell before 3d
why are transition metals and their compounds good catalysts
they can change oxidation states by gaining or losing electrons within their d-orbitals
this means they can transfer electrons to speed up reactions.
theyre also good at adsorbing substances onto their surfaces to lower activation energy of reactions
name 3 industry uses of transition metals as catalysts
1) haber process, Fe
2) MnO2 is used in the decomposition of hydroge peroxide
3) production of hydrogen from zinc and acids, CuSO4 used as catalyst
name 4 chemical proeprties of transition metals
- form complex ions
- form coloured ions
- good catalysts
- exist in variable oxidation states
define complex ion
a metal ion surrounded by coordinately bonded ligands
define ligand
an atom, ion or molecule that donates a pair of electrons to a central metal ion in a complex ion
define coorinate bond
(dative covalent bond)
a covalent bond in which both electrons in the shared pair come from the same atom
define monodentate ligand
a ligand that can only form one coordinate bond
define bidentate ligand
a ligand that can form 2 coordinate bonds
define multidentate ligand
a ligand that can form 3 or more coordinate bonds
define coordination number
number of coordinate bonds that are formed with the central metal ion in a complex ion
what shape and angles do complex ions have with a coordination number of 6
octahedral
90°
whats a hexaaqua complex
6 water ligands around a central ion
what shape and angles do complex ions have with a coordination number of 4
- mostly tetrahedral with 109.5° angles e.g. [CuCl4]2-, [CoCl4]2-
- some are square planar with 90° angles e.g. cisplatin [Pt(NH3)2(Cl2)]
what is concidered a large ligand and what effect does this have
Cl-
only 4 can fit around the central metal ion
draw the general shape of a tetrahedral complex ion
draw [CuCl4]2-
draw 3d structure of cisplatin [Pt(NH3)2Cl2]
draw the 2 optical isomers of [Ni(H2NCH2CH2NH2)3]2+
Cis-trans isomerism can occur on what type of complex ions
- square planar complex ions that have 2 pairs of ligands
- octahedral complex ions with 4 ligands of 1 type and 2 of another
define ligand substitutuion
a reation where 1 or more ligands are changed for one or more other ligands in a complex ion
wirte the balanced equation for
[Cr(H2O)6]3+(aq) + NH3 ⇌
[Cr(H2O)6]3+(aq) + 6NH3(aq) ⇌ [Cr(NH3)6]3+(aq) + 6H2O(l)
write the full balanced equations for the precipitatoin reactions of Iron(II) with 2OH- and 2NH3
[Fe(H2O)6]2+(aq) + 2OH-(aq) -> [Fe(OH)2(H2O)4]2+(s) + 2H2O(l)
[Fe(H2O)6]2+(aq) + 2NH3(aq) -> [Fe(OH)2(H2O)4]2+(s) + 2NH4+(aq)
write full precipitate reaction for Copper(II) with 2OH- and 2NH3
state the colour change
Cu(H2O)6]2+(aq) + 2OH-(aq) -> Cu(OH)2(H2O)4](s) + 2H2O(l)
Cu(H2O)6]2+(aq) + 2NH3(aq) -> Cu(OH)2(H2O)4](s) + 2NH4+(aq)
pale blue -> blue prcpt
write full precipitate reaction for Chromium(III) with 2OH- and 2NH3
state the colour change
[Cr(H2O)6]3+(aq) + 3OH-(aq) -> Cr(OH)3(H2O)3(s) + 3H2O(l)
[Cr(H2O)6]3+(aq) + 3NH3(aq) -> [Cr(OH)3(H2O)3](s) + 3NH4+(aq)
green -> grey-green prcpt
write full precipitate reaction for Iron(III) with 2OH- and 2NH3
state the colour change
[Fe(H2O)6]3+(aq) + 3OH-(aq) -> Fe(OH)3(H2O)3(s) + 3H2O(l)
[Fe(H2O)6]3+(aq) + 3NH3(aq) -> [Fe(OH)3(H2O)3](s) + 3NH4+(aq)
yellow -> orange prcpt
write full precipitate reaction for Manganese(II) with 2OH- and 2NH3
state the colour change
[Mn(H2O)6]2+(aq) + 2OH-(aq) -> [Mn(OH)2(H2O)4](s) + 2H2O(l)
[Mn(H2O)6]2+(aq) + 2NH3(aq) -> [Mn(OH)2(H2O)4](s) + 2NH4+(aq)
pale pink -> pink/buff prcpt
whats used as an oxidising agent for oxidising Fe2+
what ion is present and whats its oxidation state
what is it reduced to
Acidified potassium manganate(VII) solution, KMnO4(aq)
MnO4- ions
manganese has an oxidation state of +7
manganese reduced to Mn2+
WHAT reducing agent os used for Fe3+
whats it oxidised to
I-
I2
whats used as an oxidising agent for Cr3+ -> Cr2O72-
H2O2(aq)
reduced to OH-
WHATS THE REDUCING AGENT USED FOR Cr2O7 TO Cr3+
acidifed zinc
Zn oxidised to Zn+2
