Transition Metals vs. Alkali Metals (AQA GCSE Chemistry): Revision Notes

1.3.2 Transition Metals vs. Alkali Metals

Location in the Periodic Table

• Transition Metals: Found in the centre of the periodic table (Groups 3 to 12).
• Alkali Metals: Found in Group 1 on the far left of the periodic table.

Reactivity

• Transition Metals: These metals are less reactive compared to alkali metals. They don't react as quickly with water, oxygen, or acids. For example, iron rusts slowly over time when exposed to water and oxygen.
• Alkali Metals: These are highly reactive metals, especially with water and oxygen. For example, sodium (Na) reacts vigorously with water, producing hydrogen gas and heat, which can cause an explosion.

Density and Strength

• Transition Metals: They have a high density and are generally strong and hard. For example, iron (Fe) and steel (an alloy of iron) are used to build structures because of their strength.
• Alkali Metals: These metals have a low density (some can even float on water) and are soft. For example, potassium (K) can be cut easily with a knife.

Melting and Boiling Points

• Transition Metals: They have high melting and boiling points, meaning they remain solid at high temperatures. For example, tungsten (W) has one of the highest melting points of any metal.
• Alkali Metals: These metals have low melting and boiling points compared to transition metals. For example, caesium (Cs) melts just above room temperature.

Conductivity

• Both transition and alkali metals are good conductors of heat and electricity. This is why metals like copper (a transition metal) are used in electrical wiring.

Formation of Compounds

• Transition Metals: They can form a wide variety of coloured compounds and can have multiple oxidation states. For example, iron forms Fe²⁺ (green) and Fe³⁺ (yellow/brown) compounds.
• Alkali Metals: They usually form white or colourless compounds and have only one oxidation state, typically +1. For example, sodium forms Na⁺ ions in compounds like sodium chloride (table salt), which is white.

Catalytic Properties

• Transition Metals: Many of these metals and their compounds act as catalysts in chemical reactions. For example, platinum (Pt) is used in catalytic converters in cars.
• Alkali Metals: They are not typically used as catalysts.

Reactivity with Water

• Transition Metals: Generally do not react or react very slowly with water.
• Alkali Metals: React vigorously with water to produce hydrogen gas and a hydroxide. For example: