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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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Non-Newtonian fluids

Many people have heard of Sir Isaac Newton. He is famous for developing many scientific theories in mathematics and physics. Newton described how ‘normal’ liquids or fluids behave, and he ...

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Absolute dating

Geologists often need to know the age of material that they find. They use absolute dating methods, sometimes called numerical dating, to give rocks an actual date, or date range, in number of ...

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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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Cleaning up the oil spill

On 5 October 2011, the cargo vessel Rena ran aground on the Astrolabe Reef. The ship was carrying 1700 tonnes of heavy fuel oil and about 200 tonnes of diesel in its tanks. Over 360 tonnes of ...

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States of matter

Anything that has mass is made up of matter – an all-encompassing word for atoms and molecules that make up our physical world. We describe this matter as existing in states (sometimes referred ...

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The essential elements

As our knowledge of the chemistry of living systems (biochemistry) increases, we learn more about essential elements. Mammals like ourselves are thought to use only 25 of the 116 known elements ...

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Carbon cycle

The carbon cycle can seem like a complex process because there are many interacting parts. Carbon is found in both organic (living) and inorganic (non-living) forms. Before we discuss the cycle ...

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What are ceramics?

A ceramic is an inorganic non-metallic solid made up of either metal or non-metal compounds that have been shaped and then hardened by heating to high temperatures. In general, they are hard ...

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Digestion – breaking the large into the small

Digestion of food involves both physical and chemical processes. Through digestion, large food particles are converted into smaller components that can be readily absorbed into the bloodstream. ...

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What is clay?

Since the earliest times, humankind has had a close association with clay. From use as a building material, in pottery, for treating human digestive ailments to a multitude of industrial uses ...

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The human digestive system

The human digestive system consists of a long muscular tube and several accessory organs such as the salivary glandspancreas and gall bladder. It is responsible for food ingestion and digestion ...

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Chemical reactions and catalysts

A chemical reaction involves a chemical change, which happens when two or more particles (which can be molecules, atoms or ions) interact. For example, when iron and oxygen react, they change to ...

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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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Rate of digestion

Digestion of food involves chemical reactions that break up large food molecules into their ‘building block’ components. There are a number of factors that affect the rates of these reactions ...

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Using isotopes as tracers

Radioactive isotopes have many useful applications in a wide variety of situations, for example, they can be used within a plant or animal to follow the movement of certain chemicals. In ...

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Bone and tooth minerals

The minerals found in human teeth and bones that give them their hardness and strength belong to a group of minerals called biological apatites. The apatites found in bone, tooth enamel and tooth ...

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Digestion chemistry – introduction

Food plays an extremely important part in the lives of all humans. After ingestion, the food is mechanically broken down into smaller pieces and then chemically digested through the action of ...

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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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Viscosity

If you poured some water down a slope, it would flow freely and quickly, but what about if you repeated the process with honey? Can you imagine how honey would flow down a slope? Sticky oozy ...

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What is energy?

This is both a simple and complex question. Energy is in everything – it is often described as ‘the ability to do work’. Almost all food energy comes originally from sunlight. The chemical ...

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Metals, alloys and metal compounds

From titanium implants to new superconducting alloys to useful metal compounds, we are increasingly dependent on metals. Without metals, modern civilisation would literally collapse. About 80% of ...

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