Skip to notes
wise otter.Chemistry
Contents
K223 / K225 / 2027
Bonding and Structure

Lesson 4 of 5

Metals and alloys

Recognize metals and alloys and connect their properties to their arrangement.

SEC G2 2027

  • I can describe the general properties of metals.Syllabus

    Syllabus K223 / K225, 3.3(b). Describe the general properties of metals

  • I can recognise an alloy.Syllabus

    Syllabus K223 / K225, 3.3(c). Recognise an alloy

  • I can identify metals and alloys in diagrams.Syllabus

    Syllabus K223 / K225, 3.3(d). Identify metals and alloys in diagrams

Metals and alloys: properties from arrangement

Recognize a metal and an alloy, then connect structure to their different behaviour.

Metals generally have high melting and boiling points, conduct heat and electricity, and are malleable: they can be hammered into shape. Most are solids at room temperature. These are general patterns, not rules without exceptions.

An alloy is a mixture of a metal with other elements. Brass contains copper and zinc. Stainless steel contains iron and chromium, with other elements depending on its composition. Unlike a compound, an alloy need not have a fixed ratio of elements.

Pure metal: regular layers

Equal-sized atoms in regular rowsThirteen equal-sized particle symbols are arranged in regular offset rows. This compares atomic sizes and arrangement; the delocalised electrons are omitted.
One type of atom, arranged in regular layers.

Alloy: disrupted layers

A different-sized atom distorts the regular arrangementThirteen particle symbols include one larger amber atom. The smaller neighbouring atoms are displaced, so the layers are less regular. This compares atomic sizes and arrangement; the delocalised electrons are omitted.
Different-sized atoms disrupt the regular arrangement.

A simplified substitutional alloy, not to scale. Other alloys may contain smaller atoms in gaps.

A pure metal contains one type of atom. An alloy contains more than one; differently sized circles represent its different constituent atoms.

Check your understanding

Four diagrams show particles in a solid. Which one represents an alloy?

  1. Identical circles packed in regular rows with no gaps between them
  2. Alternating circles marked + and - in a regular repeating pattern
  3. Small separate pairs of joined circles, spaced far apart from each other
  4. Regular rows of identical circles with a few larger, different circles in between
Show the answer

Regular rows of identical circles with a few larger, different circles in between

An alloy is a metal mixed with another element, so it has two kinds of atom, and the different sizes break up the regular rows.

Check your understanding

Copper is used for electrical wires and for the bases of cooking pots. Which properties suit both uses?

  1. It has a low melting point and is a poor conductor of heat
  2. It is soft, has a low density and reacts readily with cold water
  3. It is brittle and conducts electricity when molten but not when solid
  4. It conducts electricity and heat well, is malleable and has a high melting point
Show the answer

It conducts electricity and heat well, is malleable and has a high melting point

Wires need a good electrical conductor that can be drawn and bent. Pot bases need a good heat conductor that does not melt on a stove.