In this lesson, we will learn:
- The Periodic Table's arrangement of metals and non-metals
- The range of metal and non-metal properties and the importance of variety in the properties of elements.
- How to classify elements as metal, non-metal or metalloids based on their properties.
- As seen in lesson Structure of the periodic table , the current Periodic Table shows elements arranged in terms of metals and non-metals. Metals are on the left whilst non-metals are found on the right of the table.
- This way of classifying elements is important because whether an element is a metal or not suggests a lot of its chemical and physical properties.
- In general, metal properties are as follows:
- Metals reflect light - they are shiny, not dull.
- Metals conduct both heat and electricity well.
- Metals have a high melting and boiling point and are solids at room temperature (except mercury).
- Metals are hard, but malleable (when heated, they can be hammered into desired shape) and ductile (they can be drawn out to form wires).
- In general, non-metals have properties opposite to metals:
- Non-metals are usually dull and don't reflect light.
- Non-metals are poor conductors of both heat and electricity.
- Non-metals have a relatively low melting and boiling point – many are gases at room temperature.
- If a non-metal is a solid at room temperature, it's normally brittle, meaning its shape cannot easily be changed or manipulated like a metal can.
- The elements in the periodic table show a spectrum of metal character. This means there is not always completely metal or non-metal properties in an element – the most important examples of these are the metalloids, or semiconductors. These elements on the border of metals and non-metals display a mix of metal and non-metal properties.
- The general trend in the periodic table shows increasing metallic character going from right to left in the table, and going down the table toward the bottom. "Increasing metallic character" means the elements will have more metal-like properties.
- Knowing the spectrum and variety of properties that different elements have is important for chemists to help choose the right material for the right use or task.