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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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Relative dating

Relative dating is used to arrange geological events, and the rocks they leave behind, in a sequence. The method of reading the order is called stratigraphy (layers of rock are called strata) ...

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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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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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Soil properties

All soils contain mineral particles, organic matter, water and air. The combinations of these determine the soil’s properties – its texture, structure, porosity, chemistry and colour. Soil ...

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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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Large intestine function

Recent research has revealed that the large intestine and its resident bacterial population have key roles to play in determining our health and wellbeing. It is much more than just a waste ...

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Ocean temperature

The temperature of the ocean determines what form the water takes. Most of the ocean is liquid water, but if it gets cold enough, it turns to solid ice, or if it gets hot enough, it can pass into ...

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Carbonate chemistry

Calcium carbonate is the principal mineral component of limestone. Its chemical and physical properties lie behind the modern-day uses of limestone as well as the unique limestone landscapes of ...

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Ocean density

The density of seawater plays a vital role in causing ocean currents and circulating heat because of the fact that dense water sinks below less dense. Salinity, temperature and depth all affect ...

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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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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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Hormonal control of digestion

It has now been well established that gut hormones have a key role in controlling food intake and energy expenditure. The gut is the body’s largest hormone-producing organ, releasing more than 20 ...

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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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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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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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Limestone uses

The calcium carbonate content of limestone rocks has been used from the earliest civilisations, dating back to 14,000 BCE, to its extensive use in modern times. It is a valuable resource that ...

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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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