Properties of transition metal compounds 204-205

Question 1

Give some generally properties of transition metal compounds.

Answer 1

• Shiny appearance
• High densities
• high melting/boiling points

Question 2

Which transition elements can be in multiple oxidation states?

Answer 2

The transition elemtns from titanium to copper all form ions with two or more oxidation states.

(Scandium only has a 3+ oxidation state and zinc only has 2+ oxidation state.)

Question 3

Explain why all transition elements can have 2+ oxidation state?

(Apart from scandium.)

Answer 3

In most cases, this is the result of losing the two electrons from the 4s orbital. The 4s electrons are lost first because they are in the higher occupied energy level.

Question 4

Write out the colours that the different transition metals have in different oxidation states.

Answer 4

Question 5

Give the systematic names of KMnO₄ and K₂Cr₂O₇and give the oxidation numbers of the transition metals in the compounds.

Answer 5

KMnO₄ is known as potassium manganate(VII) and Mn has an oxidation number of +7.

K₂Cr₂O₇ is known as potassium dichromate(VI) and has an oxidation number of Cr = +6.

Question 6

Explain how the colour we see from transition metals is not the colour the transition metals actually are.

Answer 6

The colour we observe is a mixture of the wavelengths of light that have not been absorbed. For example, a solution of copper(II) sulfate appears pale blue because the solution absorbs the red/orange region of the electromagnetic spectrum and reflects or transmits the blue.

Question 7

Explain why scandium in alls its oxidation states is colourless.

Answer 7

Scandium (II) has the electron configuration 1s²2s²2p⁶3s²3p⁶ and is colourless in aqueous solution. Scandium (III) is formed from scandium (1s²2s²2p⁶3s²3p⁶4s²3d¹) by the loss of two 4s electrons and one 3d electron. There is no partially filled d-orbital and there is no colour.

Question 8

What is usually the source of colour in inorganic compounds?

Answer 8

Transition metals with incomplete d-sub shells.