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Gaseous atmosphere

The Earth’s atmosphere is a layer of gases held close to its surface by gravity. It plays a crucial role in supporting plant and animal life, helps to maintain a global average surface ...

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How elements are formed

Our world is made of elements and combinations of elements called compounds. An element is a pure substance made of atoms that are all of the same type. At present, 116 elements are known, and ...

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The nitrogen cycle

Nitrogen is the most abundant element in our planet’s atmosphere. Approximately 78% of the atmosphere is made up of nitrogen gas (N2). Nitrogen is a crucially important component for all life. It ...

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What is fire?

Fire is the visible effect of the process of combustion – a special type of chemical reaction. It occurs between oxygen in the air and some sort of fuel. The products from the chemical reaction ...

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Development of the periodic table

Although elements such as gold, silver, tin, copper, lead and mercury have been known since earliest times, the first scientific discovery of an element occurred in 1649. Hennig Brand, a German ...

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What is smoke?

What is smoke and why do some fires seem to have more smoke than others? Smoke is a collection of tiny solid, liquid and gas particles. Although smoke can contain hundreds of different chemicals ...

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Fire behaviour

Fires behave differently. Some burn slowly and evenly; others are extremely hot, burning fiercely and quickly. Different fires have different coloured flames. Some fires start easily; others ...

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Non-renewable energy sources

Energy comes from many sources, and to describe these sources we use two terms: renewable and non-renewable. Non-renewable energy resources cannot be replaced – once they are used up, they will ...

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Water density

Water density changes with temperature and salinity. Density is measured as mass (g) per unit of volume (cm³). Water is densest at 3.98°C and is least dense at 0°C (freezing point). Why does ice ...

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Water and ice

Looking down at the Earth from space, you can get an idea of just how much water there is. In fact, around 71% of the Earth’s surface is covered in water. Oceans make up about 97% of the world’s ...

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Light and telescopes

The universe is full of amazing things, but we need help to see most of them. There are many types of light that our eyes cannot see, so we use instruments, such as telescopes, that can detect ...

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Lightning explained

Lightning is a large-scale natural spark discharge that occurs within the atmosphere or between the atmosphere and the Earth’s surface. On discharge, a highly electrically conductive plasma ...

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Soil formation

New Zealand has a wide variety of landscapes. A day’s sightseeing journey might include volcanic plateaus, rolling hills, river basins and coastal lands. It is easy to notice how the scenery ...

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Distances in space

Distances in space are really, really big. The Voyager 1 spacecraft is heading out of our Solar System at 62,000 km per hour, but even at that speed, it would take it 77,000 years to reach the ...

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Energy sources through time – timeline

Use this timeline to explore how humans have relied on fossil fuels in the past and how we are looking for, and using, new energy sources. 200,000 BC - Fire used Records of the first controlled ...

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Plasmas explained

We happily live in the Earth’s gaseous lower atmosphere composed of a mixture of gases – primarily nitrogen and oxygen. However, if we move upwards from the Earth’s surface, the environment ...

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