Chapter 24 Transition elements (excluding colours)

define d-block elements

have 3d subshell as having the highest energy level

properties of d-block elements

high melting points/boiling points

shiny in appearance

conduct electricity/heat

define transition elements

d-block elements that form one or more stable ions with partially filled d-subshells

Cr as an exception in electron configuration

half-filled d⁵ subshell adds stability

Cu as an exception in electron configuration

fully-filled d¹⁰ subshell adds stability

d-block elements lose their 4s electrons before losing any of the 3d electrons meaning that…

when forming an atom the 4s orbital fills before the 3d orbitals

when forming an ion the 4s orbital empties before the 3d orbitals

Sc as a d-block element but not a transition element

Sc³⁺ has an electron configuration of 1s²2s²2p⁶3s²3p⁶

has no d-orbitals

Zn as a d-block element but not a transition element

Zn²⁺ has an electron configuration of 1s²2s²2p⁶3s²3p⁶3d¹⁰

has full d-orbitals

properties of the transition metals and their compounds

variable oxidation states

coloured compounds

act as catalysts

trend of oxidation states across the transition elements

increases across the transition elements to Mn then decreases

all of the transition elements form compounds with an oxidation number of +2

examples of transition metals as catalysts

Haber process in the production of ammonia (iron catalyst)

Contact process in the production of sulfur trioxide (V₂O₃ (s) catalyst)

hydrogenation of vegetable fats in the production of margarine (Ni catalyst)

catalytic decomposition of H₂O₂ (MnO₂ (s) catalyst)

describe the formation of complex ions

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

define ligand

a molecule or ion that donates a pair of electrons to a central metal ion to form a coordinate bond

define coordinate bond

type of covalent bond in which one of the bonded atoms provides both of the electrons for the shared pair

define coordination number

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

define monodentate ligand

a ligand that is able to donate one pair of electrons to a central metal ion

examples of monodentate ligands

H₂O

NH₃

CN^-

Cl^-

OH^-

define bidentate ligands

a ligand that is able to donate 2 pairs of electrons

examples of bidentate ligands

H₂N(CH₂)₂NH₂

C₂O₄^2-

shape of 6-coordinate complexes

octahedral

90°

shape of 4-coordinate complexes

tetrahedral, 109.5°

square-planar, 90° (platins)

shape of 2-coordinate complexes

linear

180°

define stereoisomer

same structural formula but a different arrangement of the atoms in space

2 types of stereoisomerism complex ions can display

cis-trans isomerism

optical isomerism

describe cis-trans isomerism in complex ions

occurs in octahedral and some square-planar complex-ions

describe optical isomerism in complex ions

occurs in octahedral complexes containing two or more bidentate ligands

position of ligands in cis complex ions

next to each other

position of ligands in trans complex ions

opposite each other