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Flashcards in Transition Metals Deck (22)
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1
Q

Transition metal def

A

A metal that forms one or more stable cations with a partially filled d sub-shell

2
Q

Why aren’t scandium and zinc transition metals?

A

As ions, scandium has no electrons in the d sub shell and zinc has a full d sub shell - neither are partially filled

3
Q

Why do transition metals show variable oxidation numbers?

A

The 4s sub shell and the 3d subshell have very similar energies

4
Q

Properties of transition elements

A

Have variable oxidation states, form metal complexes, from complex compounds, good catalysts, form coloured ions in solutions

5
Q

Ligand def

A

A species which can donate a lone pair of electrons to an empty d-orbital to form a dative covalent bond

6
Q

Complex ions

A

A central metal ion surrounded by ligands bonded to it by dative covalent bonds - has an overall positive or negative charge

7
Q

Naming metal complexes

A

Cations before anions. Negative ligands before neutral ones. Alphabetical. Number of a group is indicated by a prefix (di/tri/tetra). Negative ligands end in o. If the overall complex is negative, it will end in are. The oxidation state of the metal is given at the end in roman numerals

8
Q

Catalyst for margarine production

A

Ni (nickel)

9
Q

Catalyst for making SO3 for H2SO4

A

V2O5

10
Q

Catalyst for Haber process to make ammonia

A

Fe (iron)

11
Q

Catalytic converters

A

Pt (platinum) and Pd (palladium)

12
Q

Co-ordination number

A

Number of co-ordinate (dative covalent) bonds from ligands to metal ions

13
Q

What is used as a chemical test for very small concentrations of Fe3+ ions? Why?

A

Iron thiocyanate because it is very intensely coloured

14
Q

Where does the origin of coloured compounds come from?

A

Compounds either emit light of a particular frequency or they absorb light at a particular frequency

15
Q

What are the only stable oxidation states for scandium and zinc?

A

Zinc (II) and Scandium (III)

16
Q

Which sub-shell has the higher energy?

A

3d. Hence, 4s is filled first and lost first as 4s electrons have higher energy

17
Q

Why do all transition metals form 2+ ions?

A

Because the 2 4s electrons are lost

18
Q

What do high oxidation states mean for the transition element?

A

It acts as a strong oxidising agent as it can easily gain electrons from other substances

19
Q

Ligand field theory

A

Assumes that the central metal ion interacts with the surrounding ligands electrostatically. The negatively charged ligands interact with the d electrons in the cation because the d orbitals are arranged differently in space

20
Q

Why are ligands degenerate?

A

In an isolated atom or ion, before any interaction, the five atomic d-orbitals have the same energy

21
Q

Why does the degeneracy of ligands change?

A

When the ligands attach,the electric fields associated cause repulsion in the d-orbitals that increase their energies

22
Q

How can electrons be promoted from lower 3d-orbitals to upper 3d-orbitals in a transition metal complex?

A

It must have at least one electron in a lower 3d-orbital and at least one gap in an upper 3d-orbital