Transition Metals - electron config. and variable oxidation states

Question 1

Define a transition element

Answer 1

A D-block element that can form at least one stable ion with a paertialy filled d-subshell.

Question 2

how many electrons can a D subshell hold

Answer 2

10 electrons

Question 3

in period 4 how many elements are transition metals.
- which ones arent and why

Answer 3

8 are transition metals.
- Scandium and Zinc are not TMs, this is becuase they don’t form a stable ion with a partially filled d-subshell.

Question 4

How do the electrons of TMs fill up the sub shells and why

Answer 4

they start off by filling up the 4s orbittal first, and they tend to fill up singly before doubling up, this is because electrons repels each other, so cos they have low energy they fill up individiually as much as they can and then double up.

Question 5

what are the two annomalies. what are their electron configs and why are they like that (electrons don’t like sitting next to each other - repel)

Answer 5

• Chromium = [Ar] 3d5, 4s1 = the electron that supposed to be in the 4s orbital shifts to the last part of the 3d orbital, they do this to form a half filled subshell which gives them more stability.
• Copper = [Ar] 3d10, 4s1 = Here having a full 3d subshell gives it more stability than having 3d9 and 4s2 configuration.

Question 6

what is the main basis of the TMs characterisitics

Answer 6

the electron configuration

Question 7

• what stable ion can Sc form ?
• whats the electron config of Sc and explain why it can’t be a TM

Answer 7

• Sc can only form one stable ion = Sc3+
• the electron config of Sc is [Ar] 3d1, 4s2 = this does have a partially filled d-subshell but the definition of a TM says it should be a stable ion with a partially filled d-subshell
• the electron config of Sc3+ = [Ar] 3d0, 4s0 = which isnt partially filled.

Question 8

• what stable ion can Zn form ?
• whats the electron config of Zn and explain why it can’t be a TM

Answer 8

• Zn can only form one stablw ion = Zn2+
• the electron configuration of Zn is = [Ar] 3d10, 4s2
  this has a full d-subshell, so can’t be a TM.
• Zn2+ = [Ar] 3d10, 4s0 = the stable ion doesnt have a full d-subshell as it loses the 4s electrons first.

Question 9

what orbital does the electrons of TMs lose first

Answer 9

they lose the 4s orbitals electrons first then the 3ds - subshell.

Question 10

List the properties of TMs

Answer 10

they have specific properties which include variable oxidatin states, formation of coloured ions, act as catalysts and their complex formations.

Question 11

what are the colours of the compounds formed of Sc and Zn and why

Answer 11

they both form white compounds as they have no electrons in the d-subshell.

Question 12

why do TMs have variable oxidation states. and what does it result in

Answer 12

TMs have their electrons sitting in 4s and 3d eneergy levels, these two very close to each othe.
- as a result electrons are gained and lost using a similar amount of energy when they form ions.
- so they have variable OS.

Question 13

what ions can vanadium form, and what is the OS of V in each one and what colour solution does each one form when dissolved in water ?

Answer 13

VO2^+ Oxidation state +5 - yellow solution
VO^2+ Oxidation state + 4 - blue solution
V^3+ Oxidation state + 3 - green solution
V^2+ Oxidation state + 2 - violet solution

Question 14

whats the colour of the sol formed from V^3+

Answer 14

green solution

Question 15

whats the colour of the sol formed from V^2+

Answer 15

violet solution

Question 16

whats the colour of the sol formed from VO^2+ (also known as V() vanadate ions

Answer 16

blue solution

Question 17

whats the colour of the sol formed from VO2^+

Answer 17

yellow solution.

Question 18

ions formed by Chromium

Answer 18

Cr^3+
Cr2O7^2-

Question 19

whats the colour of the sol formed from Cr^3+

Answer 19

when normally substituted = green
but when surrounded by 6H2O = violet

Question 20

whats the colour of the sol formed from Cr2O7^2-

Answer 20

Orange solution

Question 21

ions formed by manganese

Answer 21

Mn^2+
MnO4^-
MnO4^2-

Question 22

whats the colour of the sol formed from Mn^2+

Answer 22

pale pink

Question 23

whats the colour of the sol formed from MnO4^-

Answer 23

Purple

Question 24

ions formed by iron

Answer 24

Fe^2+
Fe^3+

Question 25

whats the colour of the sol formed from Fe^2+

Answer 25

pale green solution

Question 26

whats the colour of the sol formed from Fe^3+

Answer 26

when surrouned by 6 water ligands they are purple.
- but the sol may appear yellow instead cos of a hydrolysis reaction.

Question 27

whats the colour of the sol formed from Nickels only stable ion

Answer 27

Ni^2+ = green solution

Question 28

• whats the colour of the sol formed from Copper only stable ion

Answer 28

Cu2+ = blue

Question 29

whats the colour of the sol formed from MnO4^2-

Answer 29

green

Question 30

what can be used to reduce Vanadium ions - VO2^+

Answer 30

Zinc

Question 31

what order of ions and colours does the vanadium ion reduce to when added with zinc in an acidic solution

Answer 31

VO2^+ = yellow ->
2VO2^+(aq) + Zn(s) + H^+ => 2VO^3+(aq) +Zn^2(aq)+ +H2O (l)
-> VO^2+ = blue ->
-> V^3+ = green ->
-> V^2+ = violet