Chapter 24 - Transition elements

Question 1

Which two elements don’t follow the typical electron figuration?

Answer 1

Chromium and copper

Question 2

Why isn’t scandium classified as a transition metal?

Answer 2

A transition metal forms at least one ion with a partially filled d-orbital
Scandium forms Sc3+ by losing two 4S electrons and one 3D

Question 3

Why isn’t zinc classified as a transition metal?

Answer 3

Zn2+ has a full d-orbital

Question 4

Characteristics of transition metals

Answer 4

The element can have variable oxidation states
They form coloured compounds
Can act as catalysts

Question 5

Which transition metal has the largest amount of oxidation states?

Answer 5

Manganese

Question 6

What colour is iron (II)?

Answer 6

Pale green

Question 7

What colour is iron (III)?

Answer 7

Yellow

Question 8

What colour is Cr (III)?

Answer 8

Green

Question 9

What colour is Cr (VI)?

Answer 9

Dark yellow

Question 10

What catalyst is used in the Haber process?

Answer 10

Iron

Question 11

What catalyst is used in the Contact process?

Answer 11

Vanadium oxide

Question 12

What catalyst is used to hydrogenate vegetable fats?

Answer 12

Nickel

Question 13

What catalyst is used to decompose hydrogen peroxide?

Answer 13

Manganese oxide

Question 14

What are heterogenous catalysts?

Answer 14

The catalyst is in a different state to the reactants

Question 15

What are homogenous catalysts?

Answer 15

The catalyst is in the same state as the reactants

Question 16

When will a complex ion form?

Answer 16

When one or more molecules bond to a central atom

Question 17

What is a ligand?

Answer 17

A molecule that donates a pair of atoms to a central molecule to form a dative covalent bond

Question 18

What is the coordinate number?

Answer 18

The number of coordinate bonds attached to that atom

Question 19

What is a monodentate ligand?

Answer 19

It is able to donate one pair of electrons to the central atom

Question 20

What are bidentate ligands?

Answer 20

Able to donate two pairs of electrons to a central atom

Question 21

What is the shape of a complex ion with a coordination number of 6?

Answer 21

Octahedral

Question 22

When will a complex ion form a tetrahedral shape?

Answer 22

When it has a coordination number of 4

Question 23

When will a complex ion form a square planar shape?

Answer 23

When it has a coordination number of 4 and the ion is of a transition metal

Question 24

When will a complex ion exist as cis-trans isomers?

Answer 24

When octahedral complexes consist of four of one type of ligand and two of another type

Question 25

When will optical isomerism occur?

Answer 25

Octahedral complexes containing 2+ bidentate ligands

Question 26

What is a ligand substitution reaction?

Answer 26

One ligand or complex ion is replaced by another

Question 27

What colour is the solution formed when copper (II) sulphate is dissolved in water?

Answer 27

Pale blue

Question 28

What happens when excess ammonia is added to [Cu(H2O)6]?

Answer 28

Four water ligands are replaced by four ammonia ligands In the first stage of the reaction, pale blue Cu(OH)2 is formed Cu(OH)2 dissolves to form a darker blue solution

Question 29

What happens when excess HCl is added to [Cu(H2O)6]?

Answer 29

Six water ligands are replaced by 4 chloride ligands | Pale blue solution changes yellow

Question 30

What complex ion is formed when chromium (II) potassium sulphate is dissolved in water?

Answer 30

[Cr(H2O)6]3+

Question 31

What colour is [Cr(H2O)6]?

Answer 31

Pale purple

Question 32

Which complex ion is formed when chromium (II) sulfate is dissolved in water?

Answer 32

[Cr(H2O)5 SO4]+

Question 33

Describe the reaction that occurs when ammonia is added to [Cr(H2O)6] 3+

Answer 33

Initially, grey-green Cr(OH)3 is formed | This dissolves in the ammonia to form [Cr(NH3)6]3+

Question 34

What happens when carbon monoxide is breathed in?

Answer 34

A ligand substitution reaction takes place - oxygen in oxyhemoglobin is replaced by carbon monoxide

Question 35

What is a precipitation reaction?

Answer 35

Two aqueous solutions form an insoluble ionic solid

Question 36

What is produced when Cu2+ reacts with NaOH?

Answer 36

Blue copper hydroxide is produced, which is insoluble in sodium hydroxide

Question 37

What is produced when Fe2+ reacts with NaOH?

Answer 37

``` Green iron (II) is formed, which is insoluble in NaOH Upon standing, the iron is oxidised to form iron (III) ```

Question 38

What is produced when Fe3+ reacts with NaOH?

Answer 38

Orange brown iron (III) hydroxide is formed | Insoluble in NaOH

Question 39

What is produced when Mn2+ reacts with NaOH?

Answer 39

Light brown manganese hydroxide is formed, which is insoluble in NaOH

Question 40

What happens when Cr3+ reacts with NaOH?

Answer 40

Grey-green chromium hydroxide is formed, which is soluble in NaOH and forms a green solution

Question 41

What happens to Fe2+ when it is titrated?

Answer 41

Oxidised to Fe3+

Question 42

What happens to MnO4- when it is titrated?

Answer 42

Reduced to Mn2+

Question 43

What colour are dichromate ions?

Answer 43

Orange

Question 44

What colour are chromium ions?

Answer 44

Green

Question 45

How are dichromate ions changed into chromium ions?

Answer 45

Addition of zinc - Cr2O72- is reduced

Question 46

Equation for the oxidation of Cr3+ to CrO42-

Answer 46

3H2O2 + 2Cr3+ + 10OH- -> 2CrO42- + 8H2O

Question 47

What happens when I- reacts with Cu2+?

Answer 47

I- is oxidised to I2 | Cu2+ is reduced to Cu+

Question 48

Equation for I- reacting with Cu2+

Answer 48

2Cu2+ +4I- ->2CuI + I2

Question 49

How to test for the ammonium ion?

Answer 49

NaOH is heated with the solution being analysed | If ammonia is present, litmus paper will turn red

Question 50

What is a ligand substitution reaction?

Answer 50

One ligand in a complex ion will be replaced by another

Question 51

What colour is the solution formed when copper (II) sulfate is dissolved in water?

Answer 51

Pale blue

Question 52

What happens when excess ammonia is added to a solution containing [Cu(H2O)6] and why?

Answer 52

The pale blue colour changes to a dark blue one | 4 ammonia molecules have replaced 4 of the water molecules in the complex ion