8.4The Periodic Table
Transition elements — Combined Science 0653 - Chemistry Revision Notes & Topical Questions
5 min read 16 parts Lesson 7 of 8 1 quiz
Lesson summary
8.4 Transition elements — COMBINED SCIENCE (CHEMISTRY) notes: Describe the position, properties and uses of the transition elements.Position — transition elements are in the centre of the Periodic Table between Group II and Group III.Typical metal properties — they are lustrous, …
- Ions with different charges
- Coloured compounds
- Several oxidation numbers
- Scandium and zinc
- Transition metals
- Haber process
Section 1 of 16Position and general properties
Position
- Position transition elements are in the centre of the Periodic Table between Group II and Group III.
Typical metal properties
- Typical metal properties they are lustrous, hard, strong, good conductors of heat and electricity and have high melting points.
- Mercury is an exception because it is a liquid at room temperature.
Section 2 of 16Properties that are special to transition elements
Properties that are special to transition elements
Ions with different charges
- Ions with different charges iron forms Fe2+ and Fe3+ ions.
Catalysts
- Catalysts iron is the catalyst in the Haber process.
Coloured compounds
- Coloured compounds copper forms blue copper sulfate, black copper oxide and green copper carbonate.
Section 3 of 16Oxidation numbers (supplement)
1Several oxidation numbers
- Several oxidation numbers transition elements can lose different numbers of electrons.
- Iron forms Fe2+ with oxidation number +2 and Fe3+ with +3.
2Properties
- Properties compounds with different oxidation states have different properties and colours.
Section 4 of 16Elements that are not transition elements
- Scandium and zinc
- are in the transition block but do not form coloured compounds and have only one oxidation state.
Section 5 of 16Colours of common ions
| Ion | Compound colour |
|---|---|
| Cu2+ | Blue |
| Fe2+ | Green |
| Fe3+ | Red-brown |
Section 6 of 16Name
- Transition metals
- transition elements are also called transition metals.
Section 7 of 16More from the specification
More from the specification
Periodic trends in d-block elements
- Periodic trends in d-block elements transition metals show uniform horizontal trends,
- forming high-melting solid crystals through incomplete d sub-level electron shells.
Noble gases
- The Group 0 elements, which are unreactive monatomic gases
Physical property
- A property observed or measured without changing the material.
Transition metal characteristics
- High melting points, high densities, catalytic activity, and formation of distinctively coloured compounds.
Reactivity compared to Group 1
- Transition metals react much more slowly with air and water than highly reactive alkali metals like potassium and sodium.
Variable oxidation states
- Elements such as iron, copper, and manganese can form stable cations with multiple oxidation states (e.g. Fe2+ and Fe3+).
Halogen displacement in solution
- Halogens like chlorine oxidize halide ions in solution, displacing less reactive bromine and iodine.
Trend
- General pattern down a group or across a period.
Observation
- What is seen, heard, smelt or measured
Aqueous
- Dissolved in water.
Displacement
- A reaction in which a more reactive element takes the place of a less reactive one in a compound.
Shell
- An energy level around the nucleus that holds a limited number of electrons.
Displacement reaction
- A more reactive element replaces a less reactive one in a compound
Alkali metals
- The Group I metals, which form alkaline solutions with water.
Outer shell
- Highest-energy occupied shell.
Reactive
- Reacts easily.
Halogens
- Group 17 non-metals that form diatomic molecules.
Halogen
- A Group VII non-metal with seven outer electrons.
Section 8 of 16Physical properties
Typical metals
- Typical metals high melting and boiling points, high density, hard and strong.
Conductors
- Conductors good conductors of heat and electricity.
Shaping
- Shaping malleable and ductile.
Mercury
- Mercury has a low melting point and is liquid at room temperature.
Section 9 of 16Comparison with Group I metals
| Property | Transition elements | Group I metals |
|---|---|---|
| Density | Higher | Low |
| Hardness | Hard and strong | Soft |
| Melting point | High | Low |
| Reactivity | Lower | Very reactive |
Section 10 of 16Coloured compounds
| Ion | Colour |
|---|---|
| Copper(II) | Blue |
| Iron(II) | Green |
| Iron(III) | Orange-brown |
| Manganate(VII) | Purple |
| Chromate | Yellow or orange |
Section 11 of 16Variable oxidation states
1Several oxidation numbers
- Several oxidation numbers a transition element can lose different numbers of electrons.
- Iron forms iron(II) and iron(III).
- Copper forms copper(I) and copper(II).
2Effect
- Effect compounds with different oxidation states have different properties and colours.
Section 12 of 16Catalysts
- Use
- transition elements and their compounds are often used as catalysts.
- Iron catalyses the Haber process.
Section 13 of 16Scandium and zinc
- Not transition elements
- they are in the block but form no coloured compounds and have only one oxidation state.
Section 14 of 16More from the specification
1Periodic table transition series trends
- Periodic table transition series trends small changes in effective nuclear charge across the 3d block explain horizontal similarities and atomic trends.
2Halogen Physical States and Colours
- At room temperature, chlorine is a pale green gas, bromine is a red-brown liquid,
- and iodine is a dark grey solid that sublimes into a purple vapour.
3Halogen Displacement Reactions in Water
- A more reactive halogen displaces a less reactive halide from aqueous solution;
- adding chlorine water to potassium iodide yields iodine, turning the solution brown.
4Halogens vs Noble Gases
- Halogens (Group 7) are reactive diatomic non-metals seeking one electron,
- whereas noble gases (Group 0) possess full outer electron shells and remain unreactive monatomic gases.
5Transition Metal Contrasts
- In contrast to halogens, transition metals exhibit high melting points, variable oxidation states, catalytic abilities,
- and form colored coordination compounds.
6Noble gases
- The Group 0 elements, which are unreactive monatomic gases
7Observation
- What is seen, heard, smelt or measured
8Aqueous
- Dissolved in water.
9Displacement
- A reaction in which a more reactive element takes the place of a less reactive one in a compound.
10Shell
- An energy level around the nucleus that holds a limited number of electrons.
11Displacement reaction
- A more reactive element replaces a less reactive one in a compound
12Alkali metals
- The Group I metals, which form alkaline solutions with water.
13Outer shell
- Highest-energy occupied shell.
14Halogens
- Group 17 non-metals that form diatomic molecules.
15Halogen
- A Group VII non-metal with seven outer electrons.
16Trend
- General pattern down a group or across a period.
Section 15 of 16Key terms
| Term | Meaning |
|---|---|
| Transition element | Metal in the centre block that forms coloured compounds and has variable oxidation states. |
| Oxidation number | Number of electrons lost or gained in forming an ion. |
| Catalyst | Substance that speeds up a reaction. |
| Lustrous | Shiny. |
| Haber process | Industrial process making ammonia using an iron catalyst. |
| Term | Meaning |
|---|---|
| Transition element | Metal in the central block with coloured compounds and variable oxidation states. |
| Oxidation state | Charge or number related to electrons lost or gained. |
| Catalyst | Substance that speeds up a reaction. |
| Malleable | Can be hammered into shape. |
| Ductile | Can be drawn into wires. |
Section 16 of 16Exam technique
1
Saying transition elements form white compounds only — they form coloured compounds.
2
Saying zinc is a transition element in this course.
3
Thinking iron has only one ion — it forms Fe^{2+} and Fe^{3+}.
4
Saying mercury is solid at room temperature — it is liquid.
1
Describing mercury as typical of transition elements in melting point.
2
Assuming transition metal compounds are colourless.
3
Stating that transition metals have only one oxidation state.
4
Counting zinc as a transition element.
Marked practiceQuizzes for this lesson
Last updated: