MHT-CET Chemistry · Free notes
Transition and Inner Transition Elements — MHT-CET Chemistry
Transition and Inner Transition Elements is about two questions a paper in MHT-CET Chemistry and rarely HARD — three of its 127 past-year questions. Almost every question is one count: how many d or f electrons an atom or ion has once the right electrons are removed. That count decides which elements are transition elements, which ions are coloured, the spin-only magnetic moment, and the half-filled and filled shells behind the odd oxidation states. The rest is recall — alloys, ores and catalysts — and the lanthanoid contraction. Five pages in the book's order. Every PYQ is tagged.
The handout has every subtopic, worked example, formula and trap with answers shown. The formula sheet is the chapter’s formulas and traps alone, on one page.
Subtopic notes
The d-Block: Position, d-Electron Counts and General Properties
29 PYQsTransition elements are the d-block elements that have a partly filled d subshell in the atom or in a common ion; they sit in groups 3 to 12 as four series of ten, their ions lose the outer s electrons before any d electrons, and the half-filled and filled d subshells explain the odd configurations of chromium and copper and the high ionisation enthalpy of zinc.
Oxidation States of Transition Elements
11 PYQsTransition elements show several oxidation states because their (n−1)d and ns electrons are close in energy and can be lost in steps; the range is widest in the middle of the 3d series, at manganese (+2 to +7), narrowest at the ends — scandium +3 (and +2), zinc only +2 — and the highest state in the whole block is +8, reached by osmium in the 5d series.
Colour and Magnetism of Transition Metal Ions
35 PYQsA transition metal ion is coloured when it has unpaired d electrons that can be promoted from one d level to another by visible light, so d⁰ and d¹⁰ ions are colourless; the same unpaired electrons make it paramagnetic, with a spin-only moment of √(n(n+2)) Bohr magnetons, and iron, cobalt and nickel are also ferromagnetic.
Alloys, Ores and Catalysts of the Transition Metals
11 PYQsTransition metals mix readily into alloys because their atoms are similar in size, occur in nature as oxide, carbonate and sulphide ores, and act as catalysts because they can change oxidation state and adsorb reactants on their surfaces.
Lanthanoids and Actinoids: Membership, 4f Configurations and the Lanthanoid Contraction
41 PYQsThe inner transition elements fill the 4f subshell (lanthanoids, La to Lu) or the 5f subshell (actinoids, Ac to Lr); their stable state is +3, the empty, half-filled and filled 4f subshells explain the extra +2 and +4 states, and the steady shrinking of the Ln³⁺ ion from La to Lu — the lanthanoid contraction — makes the hydroxides less basic along the series.
Formula & revision sheet
8 formulas · 3 reference tables · 12 gotchas across all subtopics — the exam-eve cheat-sheet
Formula & revision sheet
8 formulas · 3 reference tables · 12 gotchas across all subtopics — the exam-eve cheat-sheet
Formulas (2)
Reference tables (1)
Four Transition Series in Groups 3 to 124 rows
| Series | Period | Elements | Example |
|---|---|---|---|
| 3d | 4 | Sc (21) – Zn (30) | Co, Cr, Mn, Fe |
| 4d | 5 | Y (39) – Cd (48) | Mo, Ag |
| 5d | 6 | La (57), Hf (72) – Hg (80) | Pt, Au, Hg The lanthanoids Ce–Lu sit inside this row but are f-block. |
| 6d | 7 | Ac (89), Rf (104) onward | — |
Watch out for (3)
- Using the period number as the series number→ Four Transition Series in Groups 3 to 12
- Removing the 3d electrons first→ Counting d Electrons in Atoms and Ions
- Expecting a steady rise across the series→ Hard Metals, Soft Exceptions and First Ionisation Enthalpy
Watch out for (1)
- Picking the element with most d electrons→ How Many Oxidation States, and the Highest One
Formulas (2)
Watch out for (3)
- Treating copper as always coloured→ Coloured and Colourless Ions
- Counting all the d electrons as unpaired→ Unpaired Electrons and the Spin-Only Magnetic Moment
- Calling every paramagnetic metal ferromagnetic→ Unpaired Electrons and the Spin-Only Magnetic Moment
Reference tables (1)
Alloys, Ores and Catalysts to Know6 rows
| Metal | Ores | Catalyst use |
|---|---|---|
| Cu | Chalcopyrite (copper pyrites) CuFeS₂; chalcocite Cu₂S | — |
| Zn | Calamine ZnCO₃; zincite ZnO; zinc blende ZnS | — |
| Fe | Siderite FeCO₃; limonite; haematite Fe₂O₃; magnetite Fe₃O₄ | Haber process |
| V | — | V₂O₅ in the contact process |
| Co | — | Co–Th in the Fischer–Tropsch synthesis |
| Ni | — | Hydrogenation of oils; Ni–Cr is nichrome |
Watch out for (1)
- Reading 'copper pyrites' as copper and sulphur only→ Alloys, Ores and Catalysts to Know
Formulas (3)
Reference tables (1)
Which Element Is a Lanthanoid, Which an Actinoid2 rows
| Series | Z | Members to recognise |
|---|---|---|
| Lanthanoids (4f) | 57–71 | La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu |
| Actinoids (5f) | 89–103 | Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr All actinoids are radioactive. |
Watch out for (4)
- Matching by the ending of the name→ Which Element Is a Lanthanoid, Which an Actinoid
- Expecting f⁷ at +3 for europium→ 4f Configurations and the +2 and +4 States
- Picking Yb as the smallest ion→ The Lanthanoid Contraction: Size, Basicity and Ionisation Enthalpy
- Assuming every lanthanoid is stable→ Lanthanoid Compounds and General Properties
PYQ weightage by concept
11 concepts · 127 PYQs — where the marks actually sit, so you know what to drill first
PYQ weightage by concept
11 concepts · 127 PYQs — where the marks actually sit, so you know what to drill first
| Concept | PYQs | Share |
|---|---|---|
| Four Transition Series in Groups 3 to 12 | 7 | 6% |
| Counting d Electrons in Atoms and Ions | 6 | 5% |
| Hard Metals, Soft Exceptions and First Ionisation Enthalpy | 5 | 4% |
| Concept | PYQs | Share |
|---|---|---|
| How Many Oxidation States, and the Highest One | 6 | 5% |
| Concept | PYQs | Share |
|---|---|---|
| Unpaired Electrons and the Spin-Only Magnetic Moment | 14 | 11% |
| Coloured and Colourless Ions | 4 | 3% |
| Concept | PYQs | Share |
|---|---|---|
| Alloys, Ores and Catalysts to Know | 7 | 6% |
| Concept | PYQs | Share |
|---|---|---|
| Which Element Is a Lanthanoid, Which an Actinoid | 8 | 6% |
| 4f Configurations and the +2 and +4 States | 7 | 6% |
| The Lanthanoid Contraction: Size, Basicity and Ionisation Enthalpy | 7 | 6% |
| Lanthanoid Compounds and General Properties | 5 | 4% |
Test yourself on Transition and Inner Transition Elements
20 past MHT-CET questions from this chapter, timed at 18 minutes and marked the way the exam marks it. You see your score and every answer the moment you finish. Free to start.