The Earth's Surface – GCSE Chemistry (Triple) CCEA Revision

The Earth’s Surface and Its Composition

The Earth’s crust is made up of a number of elements, the most abundant of which are: oxygen (46.6%), silicon (27.7%), aluminium (8.1%), iron (5.0%), calcium (3.6%), sodium (2.8%), potassium (2.6%) and magnesium (2.1%).
The Earth’s crust is divided into large plates (tectonic plates), which float on the semi-liquid mantle beneath.
In areas where these plates meet, the crust becomes unstable and it can result in earthquakes and volcanic activity.

Minerals are naturally occurring solid compounds, which have a crystalline structure. Most of the Earth’s crust is made up of minerals like feldspar and quartz.
An ore is a rock that contains enough of a certain mineral (or minerals) for it to be worth extracting.
For instance, bauxite is an ore of aluminium, and hematite is an ore of iron.

Metals are obtained from their ores by a process called metallurgical process.
Metallurgical processes involve a number of steps, including: 1) crushing and grinding the ore into a powder, 2) separating the valuable mineral from the uneconomic fraction (known as ‘gangue’), 3) converting the valuable mineral into a metal or a compound of the metal, and then 4) purifying the metal if necessary.
Aluminium is extracted from bauxite using a process called the Bayer’s process followed by electrolysis. Iron is extracted from its ores using blast furnaces.

The continuous mining of ores and use of metals has led to a decrease in the Earth’s natural resources. To mitigate this, we need to reduce, reuse, and recycle our resources.
Recycling metals could significantly reduce the negative impact on the environment, as it requires less energy compared to extraction from its ore.
Use of alternative materials like polymers, ceramics and composites in place of metals can also help to preserve resources.

Extraction of minerals and ores from the Earth’s crust can have severe environmental consequences, such as soil degradation, air and water pollution, and biodiversity loss.
Acid mine drainage can occur when sulphide minerals in the rocks react with air and water to produce sulphuric acid, harming local ecosystems.
Several strategies can be implemented to minimise the impact of mining, including careful planning, rehabilitation of mining sites, and the use of cleaner, more efficient extraction technologies.