The reactivity series of metals
The A list of elements in order of their reactivity, usually from most reactive to least reactive. of Shiny element that is a good conductor of electricity and heat, and which forms basic oxides. is a chart showing metals in order of decreasing A measure of how vigorously a substance will react. The more reactive it is, the greater its reactivity and the more vigorous its reactions will be.. In general, the more The tendency of a substance to undergo a chemical reaction. a metal is:
- the more vigorous its reactions are
- the more easily it loses Subatomic particle, with a negative charge and a negligible mass relative to protons and neutrons. in reactions to form An atom or group of atoms that have lost electrons and become positively charged. Most cations are formed from metals.
The table summarises some reactions of metals in the reactivity series. Hydrogen is shown for comparison.
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Reaction of metals with water
When a metal reacts with water, a metal hydroxide and hydrogen are formed. For example, sodium reacts rapidly with cold water:
sodium + water → sodium hydroxide + hydrogen
2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)
In general, the more reactive the metal, the more rapid the reaction is. Aluminium is unusual because it is a reactive metal that does not react with water. Its surface naturally forms a very thin layer of aluminium oxide that keeps water away from the metal below.
Reactions with steam
Magnesium reacts slowly when it is first added to water, but a layer of Unable to dissolve in a particular solvent. For example, sand is insoluble in water. magnesium hydroxide forms. This protects the metal and stops it reacting. However, if steam is passed over hot magnesium, a vigorous reaction happens:
magnesium + steam → magnesium oxide + hydrogen
Mg(s) + H2O(g) → MgO(s) + H2(g)
In this reaction:
- magnesium is Chemical substances are oxidised by the addition of oxygen, removal of hydrogen or the removal of electrons. because it gains oxygen to form magnesium oxide
- water is A substance is reduced if it loses oxygen or gains electrons. because it loses oxygen to form hydrogen
Question
State the difference between the products formed when calcium reacts with cold water and when it reacts with steam.
Calcium hydroxide forms when it reacts with water, but calcium oxide forms when it reacts with steam.
Reaction of metals with dilute acids
When a metal reacts with a dilute Substance producing more hydrogen ions than hydroxide ions when dissolved in water. , a The substance formed when the hydrogen ion in an acid is replaced by a metal ion. and hydrogen are formed. For example, magnesium reacts rapidly with dilute hydrochloric acid:
magnesium + hydrochloric acid → magnesium chloride + hydrogen
Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)
The more reactive the metal, the more rapid the reaction is. A metal below hydrogen in the reactivity series will not react with dilute acids.
Question
Platinum is placed below gold in the reactivity series. Predict its reaction with dilute acids and explain your answer.
Platinum will not react with dilute acids. Metals below hydrogen in the reactivity series do not react with dilute acids. Both gold and platinum are placed below hydrogen.
