Chapter 24 - Transition Elements Flashcards
What are the physical properties of d block elements?
Typical physical properties of metals - metallic.
High melting points and boiling points, shiny in appearance and conduct electricity and heat
Which 2 d block elements do not follow typical electron configuration patterns?
Copper - 3d10 4s1
Chromium - 3d5 4s1
This is due to stability (half filled d sub shell and fully filled d sub shell gives additional stability to copper and chromium atoms)
What is the rule for orbital filling 3d/4s?
4s ALWAYS fills before the 3d orbitals
However, the 4s orbital will also empty before the 3d orbital
What is a transition element?
D block elements that form at least one ion with a partially filled d orbital
Which 2 d block elements are not classified as transition elements, and why?
Scandium - only forms ion Sc3+ with loss of 2 4s e- and 1 3d e-
Zinc - only forms ion Zn2+ with loss of 2 4s e-
What are the characteristic properties of transition elements which differentiates them from other metals?
- form compounds with different oxidation states
- form coloured compounds
- elements and their compounds can act as catalysts
Why do transition elements form different coloured compounds?
Due to the partially filled d orbitals in the transition metal ion, the colour of a solution varies with different oxidation states
How do transition metals act as catalysts?
- lower activation energy
- provide alternative reaction pathway
- speeding up the rate of reaction
- and are not used up
What are examples of homogeneous and heterogeneous transition metal catalysts?
Homogeneous = sodium thiosulfate titrations, e.g. Fe2+ as an oxidising agent
Heterogeneous = Ni catalyst in hydrogenation
What is a complex ion?
One or more molecules/negatively charged ions bonded to a single metal ion
What is a coordinate bond?
A dative covalent bond in which both electrons in the shared pair come from the same atom
What is a coordination number?
The number of coordinate bonds attached to the central metal ion
What is a ligand?
An ion or molecule with a lone pair, that forms a coordinate bond with a transition metal by donating an electron pair
What is a monodentate ligand, what are some common examples?
A ligand that is able to donate one pair of electrons to a central metal ion
H2O: :NH3 :Cl- :CN- :OH-
What is a bidentate ligand, what are some common examples?
Ligands which can donate two lone pairs of electrons to the central metal ion, forming 2 coordinate bonds
1,2-diaminoethane (en) and ethanedioate ion
Which atoms donate lone pairs in 1,2-diaminoethane (en) and ethanedioate ion?
en = each nitrogen atom donates a pair of electrons to the central metal ion
ethanedioate ion = each negatively charged oxygen atom donates a lone pair of electrons to the central metal ion
What are the types of shapes for complex ions?
Six co-ordinate complexes (octahedral)
Four co-ordinate complexes (tetrahedral, square planar)
What is the bond angle and coordination number for octahedral complex ions?
90 degrees
6
What is the bond angle and coordination number for tetrahedral and square planar complex ions?
Tetrahedral = 109.5 degrees and 4
Square planar = 90 degrees and 4
What types of stereoisomerism can you get in complex ions?
Cis trans isomerism
Optical isomerism
Which types of complex ions does cis trans isomerism occur in?
Some square planar and octahedral complex ions
How are cis and trans isomers arranged in square planar complex ions?
Cis = two identical groups are adjacent to each other (coordinate bonds between 2 ligands 90 degrees apart)
Trans = two identical groups are opposite to each other (coordinate bonds between 2 ligands 180 degrees apart)