Group 0 Noble Gases and Transition Metals
Group 0: The Noble Gases
The Group 0 elements (also called Group 8 or Group 18) are the noble gases: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) and radon (Rn).
Electron Configuration
Noble gases have full outer electron shells:
- Helium: 2
- Neon: 2.8
- Argon: 2.8.8
This full outer shell makes them extremely stable and unreactive. They do not easily gain, lose or share electrons.
Properties of Noble Gases
- Colourless, odourless gases at room temperature
- Monatomic — they exist as single atoms, not molecules (He, not He₂)
- Unreactive — they do not form compounds under normal conditions
- Non-flammable
Boiling Point Trend
| Noble gas | Boiling point (°C) |
|---|---|
| Helium | −269 |
| Neon | −246 |
| Argon | −186 |
| Krypton | −153 |
| Xenon | −108 |
Boiling points increase going down the group because the atoms get larger, so the intermolecular forces (van der Waals) between atoms are stronger, requiring more energy to overcome.
Uses of Noble Gases
- Helium — filling balloons and airships (low density, non-flammable), deep-sea breathing mixtures
- Neon — advertising signs (emits red-orange light when electricity passes through)
- Argon — filling light bulbs (provides an inert atmosphere so the filament does not oxidise), welding (shields the weld from oxygen)
Their uses relate to their inertness (unreactivity) and other specific properties.
Transition Metals
The transition metals are the block of elements found between Group 2 and Group 3 in the periodic table. Common examples include iron (Fe), copper (Cu), nickel (Ni), zinc (Zn), chromium (Cr), manganese (Mn), cobalt (Co), platinum (Pt) and gold (Au).
Properties of Transition Metals
Compared to Group 1 metals, transition metals are:
- Harder and stronger
- Higher melting points (except mercury, which is liquid at room temperature)
- Higher density
- Less reactive — they do not react vigorously with water or oxygen
| Property | Group 1 (e.g. sodium) | Transition (e.g. iron) |
|---|---|---|
| Hardness | Soft (cut with knife) | Hard |
| Density | Low (floats on water) | High |
| Melting point | Low (98°C for Na) | High (1538°C for Fe) |
| Reactivity | Very reactive | Less reactive |
Variable Oxidation States
Transition metals can form ions with different charges. For example:
- Iron can form Fe²⁺ (iron(II)) or Fe³⁺ (iron(III))
- Copper can form Cu⁺ (copper(I)) or Cu²⁺ (copper(II))
The Roman numeral in the name tells you the charge: iron(III) chloride = FeCl₃.
Coloured Compounds
Transition metal compounds are often coloured, unlike Group 1 compounds which are white:
| Compound | Colour |
|---|---|
| Copper(II) sulfate | Blue |
| Iron(II) sulfate | Green |
| Iron(III) chloride | Yellow/brown |
| Potassium manganate(VII) | Purple |
| Potassium dichromate(VI) | Orange |
Catalytic Properties
Many transition metals and their compounds are excellent catalysts:
- Iron — catalyst in the Haber process (making ammonia)
- Manganese dioxide (MnO₂) — catalyst for decomposition of hydrogen peroxide
- Nickel — catalyst for hydrogenation of vegetable oils
- Platinum/palladium/rhodium — catalytic converters in car exhausts
- Vanadium pentoxide (V₂O₅) — catalyst in the Contact process (making sulfuric acid)
A catalyst speeds up a reaction without being used up, providing an alternative reaction pathway with a lower activation energy.
Exam Tips
- Noble gases are unreactive because of their full outer shells — this must always be stated as the reason
- Know why boiling points increase down Group 0 (larger atoms, stronger intermolecular forces)
- Be able to compare transition metals to Group 1 metals in terms of hardness, density, melting point and reactivity
- Learn at least three examples of transition metals as catalysts