Elements and the Periodic Table
3. Metals and Non-Metals
Learning outcomes
- I can distinguish between metals and non-metals based on their physical and chemical properties.
- I can identify the location of metals and non-metals on the periodic table.
- I can compare properties such as conductivity, malleability, and melting point.
- I can explain how the properties of metals and non-metals affect their uses.
- I can classify unfamiliar elements as metals or non-metals using provided data.
Introduction
The periodic table contains over one hundred elements, but these elements are not all alike. Most can be grouped into two broad categories: metals and non-metals. Although both are made of atoms, they have very different physical and chemical properties.
Understanding the differences between metals and non-metals helps explain why different materials are used for different purposes. Copper is used for electrical wiring because it conducts electricity well, while oxygen is essential for respiration because it exists as a non-metal gas. By studying their properties, scientists can predict how elements will behave and choose suitable materials for specific applications.
What Are Metals and Non-Metals?
Elements can be divided into three broad groups:
- Metals
- Non-metals
- Metalloids (elements with properties of both)
Most elements on the periodic table are metals.
Only a relatively small number are non-metals.
Figure 1. Most elements are metals, while non-metals are mainly found on the upper right side of the periodic table.
Location on the Periodic Table
The periodic table helps identify whether an element is a metal or non-metal.
Metals
Metals are found:
- On the left side.
- In the centre of the periodic table.
Examples include:
- Sodium (Na)
- Magnesium (Mg)
- Aluminium (Al)
- Iron (Fe)
- Copper (Cu)
- Gold (Au)
Non-Metals
Non-metals are found:
- On the upper right side of the periodic table.
Examples include:
- Hydrogen (H)
- Carbon (C)
- Nitrogen (N)
- Oxygen (O)
- Sulfur (S)
- Chlorine (Cl)
Metalloids
Between the metals and non-metals is a zigzag "staircase."
Elements along this line are called metalloids.
Examples include:
- Silicon (Si)
- Boron (B)
- Germanium (Ge)
Metalloids have properties of both metals and non-metals.
Figure 2. The zigzag line separates most metals from non-metals, with metalloids lying along the boundary.
Physical Properties of Metals
Most metals share several common properties.
Good Conductors
Metals conduct:
- Electricity
- Heat
This is why copper and aluminium are widely used in electrical wiring.
Shiny (Lustrous)
Freshly cut metals usually have a shiny surface called metallic lustre.
Malleable
Malleable metals can be hammered into thin sheets without breaking.
Example:
Aluminium foil.
Ductile
Ductile metals can be drawn into wires.
Example:
Copper electrical wire.
High Melting Points
Many metals melt only at high temperatures.
Examples:
- Iron
- Tungsten
However, there are exceptions, such as mercury, which is liquid at room temperature.
Strong and Dense
Many metals are:
- Strong
- Hard
- Dense
This makes them useful in construction and engineering.
Figure 3. Metals are generally good conductors, shiny, malleable, and ductile.
Physical Properties of Non-Metals
Non-metals have very different properties.
Most non-metals are:
- Poor conductors of heat.
- Poor conductors of electricity.
- Dull in appearance.
- Brittle if solid.
- Lower density than metals.
Many non-metals are gases at room temperature.
Examples:
- Oxygen
- Nitrogen
- Chlorine
One non-metal, bromine, is a liquid at room temperature.
Comparing Metals and Non-Metals
| Property | Metals | Non-Metals |
|---|---|---|
| Appearance | Shiny | Usually dull |
| Conductivity | Good | Poor |
| Malleability | Malleable | Brittle if solid |
| Ductility | Ductile | Not ductile |
| Density | Usually high | Usually lower |
| Melting point | Usually high | Often lower |
| State at room temperature. | Mostly solids. | Many gases, some solids, one liquid (bromine) |
These are general trends, although there are exceptions.
Figure 4. Metals and non-metals differ in several important physical properties.
Chemical Properties
Metals and non-metals also behave differently in chemical reactions.
Metals
Metals often:
- Lose electrons to form positive ions.
- React with oxygen to form metal oxides.
- React with acids to produce hydrogen gas.
- React with water (some metals only).
Non-Metals
Non-metals often:
- Gain electrons to form negative ions.
- Form acidic oxides with oxygen.
- React by sharing electrons in covalent bonds.
These differences help determine the types of compounds they form.
Properties and Everyday Uses
The properties of elements determine how they are used.
Metals
| Metal | Property | Common Use |
|---|---|---|
| Copper | Excellent electrical conductor | Electrical wires |
| Aluminium. | Lightweight, corrosion-resistant. | Aircraft, drink cans |
| Iron | Strong | Buildings, bridges |
| Gold | Does not corrode | Jewellery, electronics |
Non-Metals
| Non-Metal. | Property | Common Use |
|---|---|---|
| Oxygen | Supports respiration | Medical oxygen |
| Carbon | Forms many compounds. | Fuels, graphite, diamonds |
| Chlorine | Kills microorganisms | Water treatment |
| Nitrogen | Unreactive | Food packaging |
Choosing materials based on their properties is an important part of engineering and technology.
Figure 5. The unique properties of metals and non-metals make them suitable for different everyday uses.
Classifying Unfamiliar Elements
Scientists can often identify whether an unknown element is a metal or a non-metal by examining its properties.
For example:
| Observation | Likely Classification |
|---|---|
| Conducts electricity well | Metal |
| Brittle and dull | Non-metal |
| Malleable and shiny | Metal |
| Gas at room temperature. | Usually non-metal |
| Poor conductor of heat | Usually non-metal |
Scientists use evidence rather than memorisation to classify elements.
Worked Example
Question
An unknown element has the following properties:
- Shiny
- Conducts electricity
- Can be hammered into thin sheets
- High melting point
Would it most likely be a metal or a non-metal?
Solution
Answer: Metal
Explanation:
These are all typical properties of metals.
Real-World Connection
Modern technology depends on both metals and non-metals. Smartphones contain metals such as copper, gold, and lithium, which conduct electricity and store energy, while non-metals such as silicon (a metalloid) are used to make computer chips. Engineers choose materials carefully based on their physical and chemical properties to produce safe, reliable, and efficient devices.
Did You Know?
Mercury (Hg) is the only metal that is liquid at room temperature, while bromine (Br) is the only non-metal that is liquid at room temperature. Most other metals are solids, and many non-metals are gases under the same conditions.
Key Terms
Brittle – Easily broken or shattered when struck.
Conductor – A material that allows heat or electricity to pass through easily.
Ductile – Able to be drawn into wires.
Lustre – The shiny appearance of a material.
Malleable – Able to be hammered or rolled into thin sheets without breaking.
Metalloid – An element with properties intermediate between those of metals and non-metals.
Metal – An element that is usually shiny, conducts heat and electricity, and is malleable and ductile.
Non-metal – An element that is generally a poor conductor of heat and electricity and is often dull and brittle if solid.
Periodic table – A chart that organises elements according to their atomic number and properties.
Key Takeaways
- Most elements are classified as metals or non-metals, with a small group of metalloids between them.
- Metals are generally shiny, good conductors, malleable, ductile, and have high melting points.
- Non-metals are generally poor conductors, often dull, brittle if solid, and many exist as gases at room temperature.
- The location of an element on the periodic table provides clues about whether it is a metal or a non-metal.
- The physical and chemical properties of elements determine their uses in everyday life.
- Scientists classify unfamiliar elements by examining their measurable properties rather than relying only on their names or positions on the periodic table.