Please enable JavaScript.
Coggle requires JavaScript to display documents.
Chapter 24 - Transition elements - Coggle Diagram
Chapter 24 - Transition elements
D block elements
Metallic, high melting and boiling points, shiny in appearance
Highest energy electron is in d orbital
4s sub shell has a lower energy than the 3d sub-shell
4s electrons are lost before 3s when forming an ion
Copper
Instead of [Ar] 4s23d10, its more stable if 3d subshell is completely filled, so configuration is 4s1 3d10
Instead of [Ar] 4s2 3d4, its more stable if one of the electrons from 4s in in the 3d orbital so each 3d orbital has one unpaired electron
Transition elements
D block elemts that form atleast one ion with a partially filled d-orbital
Scandium only forms SC 3+ by loss of 2 4s electrons and one 3d electrons
Zinc only forms Zn2+ ion by loss of two 4s electrons
Sc3+ have empty d-orbitals and Zn2+ have full d-orbitals
Scandium and zinc don't form ions with partially filled d-orbitals and aren't transition elements
Properties
Form compounds in which transition elements has different oxidations states
Form coloured compounds
Elemnts and compounds act as catalysts
Species containing transition element in its highest oxidation state is often a strong oxidising agent
Catalysts
Examples
Haber process uses iron catalyst
Contact process is catalysed by vanadium oxide
Homogeneous
catalyst is in same physical state as reactants
Intermediate formed
Heterogeneous
catalyst is in different state to the reactants
Adsorbtion onto surface of catalyst, bonds weaken, and reaction occurs, desorbtion off surface of catalyst
Auto catalysis
Products of reaction acts as a catalyst
As reation progresses, product increases and reaction speeds up
Complex ions
Transition metal bonded to ligands by coordinate bonds dative covalent bonds)
Coordinate number - total number of coordinate bonds formed betwen central metal ion and ligands
Coordinate bond - special kind of covalent bond when one of bonded atoms provides both of the electrons for shared pair
Representing
Complex ion enclosed inside square brackets with overall charge outside square brackets
Overall charge is the sum of the charges on the central metal ion and any ligands present
Ligand is in round brackets, number of ligands is shown outside round brackets
Ligand - molecule or ion with a lone pair that from a dative (coordinate) bond by donating a pair of electrons to transition metal ion
Ligands
Monodentate
Able to donate one pair of electrons to a central metal ion
H20, NH3
Usually has lone pair of electrons
Bidentate
Can donate two pairs of electrons to central metal ion - two coordinate bonds formed
1,2 diaminoethane
Each nitrogen atom donates a pair of electrons to the central metal ion forming a coorindate bond
Shapes of complex ions
Six-coordinate complexes
Octahedral shape
Bond angle of 90 degrees
Four coordinate complexes
Tetrahedral
Angle of 109.5
[CoCl4]2-
Square planar
Occurs in copmlex ions of transition metals with 8 d-electrons in highest energy sub-shell
Platinum, palladium and gold
Angle of 90
