Metals and Non-metals

The One Thing

The electron behaviour of metals and non-metals determines their reactions, the formation and properties of ionic compounds, the displacement of metals, corrosion, and the extraction methods used for metals. The reactivity series provides the main framework for predicting these processes.

Reactions, Processes and Experiments

Key Terms

• Metal: An element that usually loses electrons, forms positive ions, and shows properties such as lustre, malleability, ductility, and good conductivity.
• Non-metal: An element that generally gains or shares electrons and is usually brittle in the solid state and a poor conductor of heat and electricity.
• Malleability: The ability of a metal to be beaten into thin sheets.
• Ductility: The ability of a metal to be drawn into thin wires.
• Sonority: The property of producing a ringing sound when struck.
• Reactivity series: An arrangement of metals in decreasing order of their reactivity: potassium, sodium, calcium, magnesium, aluminium, carbon, zinc, iron, tin, lead, hydrogen, copper, mercury, silver, gold, and platinum.
• Ionic compound: A compound formed by the transfer of electrons from one atom to another, producing oppositely charged ions held by strong electrostatic forces.
• Cation: A positively charged ion formed when an atom loses electrons.
• Anion: A negatively charged ion formed when an atom gains electrons.
• Valency: The combining capacity of an element. Common examples include sodium 1, magnesium 2, aluminium 3, chlorine 1, oxygen 2, and nitrogen 3.
• Ore: A naturally occurring mineral from which a metal can be extracted economically.
• Gangue: Unwanted earthy or rocky impurities mixed with an ore.
• Mineral: A naturally occurring substance containing a metal or its compounds.
• Metallurgy: The process of extracting metals from their ores and purifying them.
• Roasting: Heating a sulphide ore strongly in excess air to convert it into a metal oxide.
• Calcination: Heating a carbonate ore strongly in limited or no air to convert it into a metal oxide.
• Reduction: Removal of oxygen from a metal oxide or addition of electrons to a substance.
• Refining: Purification of an impure metal, often by electrolytic refining.
• Alloy: A homogeneous mixture of two or more metals, or a metal and a non-metal, made to improve useful properties.
• Amphoteric oxide: An oxide that reacts with both acids and bases, such as aluminium oxide and zinc oxide.
• Corrosion: The slow deterioration of a metal due to reactions with substances in the environment.
• Galvanisation: Coating iron or steel with zinc to protect it from corrosion.
• Oxidation: Addition of oxygen or removal of electrons from a substance.
• Displacement reaction: A reaction in which a more reactive metal displaces a less reactive metal from its salt solution.

Easily Confused

• Roasting and calcination: Roasting heats a sulphide ore in excess air, whereas calcination heats a carbonate ore in limited or no air.
• Reduction and refining: Reduction converts a metal oxide into the metal, whereas refining purifies an already extracted but impure metal.
• Mineral and ore: A mineral contains a metal or its compounds, whereas an ore is a mineral from which the metal can be extracted economically.
• Cation and anion: A cation is positively charged because it has lost electrons; an anion is negatively charged because it has gained electrons.
• Malleability and ductility: Malleability is the ability to form thin sheets; ductility is the ability to form thin wires.
• Metal oxides and non-metal oxides: Metal oxides are generally basic, whereas most non-metal oxides are acidic or neutral.
• Ionic compounds in the solid and molten or aqueous states: Ionic compounds do not conduct electricity in the solid state but conduct when molten or dissolved in water.
• Galvanisation and electroplating: Galvanisation specifically coats iron or steel with zinc, whereas electroplating deposits a selected coating by electrolysis.
• General corrosion and rusting: Corrosion is the deterioration of a metal generally; rusting is the corrosion of iron requiring both oxygen and water.
• Reactivity and occurrence: Highly reactive metals such as potassium, sodium, calcium, magnesium, and aluminium require electrolysis, whereas low-reactivity metals such as copper, silver, gold, and platinum may occur in the free state or be extracted by simpler methods.
• General physical properties and exceptions: Metals are generally malleable, ductile, sonorous, and good conductors, but mercury is liquid at room temperature, sodium and potassium are soft, and graphite, a non-metal, conducts electricity.

What Gets Asked

• Writing and interpreting reaction equations: Questions may require the general reaction of a metal with oxygen, such as Metal + Oxygen → Metal oxide, or the specific equation 2Mg + O2 → 2MgO. Marks are lost by omitting or misidentifying the product.
• Comparing reactions with water and acids: Questions may ask how potassium, sodium, calcium, magnesium, and iron react with water, or why metals above hydrogen displace hydrogen from dilute acids. Marks are lost by treating all metals as equally reactive.
• Predicting displacement reactions: A question may use Fe + CuSO4 → FeSO4 + Cu and ask whether displacement occurs. The key slip is failing to compare the positions of the metals in the reactivity series.
• Explaining ionic compound formation and properties: Questions may involve sodium chloride formation, valency, or formulae such as MgCl2, Al2O3, and CaCl2. Marks are lost when the formula does not have overall electrical neutrality or when solid ionic compounds are incorrectly said to conduct electricity.
• Selecting an extraction method: Questions may ask whether electrolysis, reduction with carbon or carbon monoxide, or a simpler method is appropriate. The method must be matched to the metal’s position in the reactivity series.
• Distinguishing extraction, refining, and corrosion prevention: Questions may ask about roasting, calcination, reduction, electrolytic refining of copper, rusting, or galvanisation. Marks are lost by confusing conversion of an ore into a metal with purification or protection of the metal.