Leçons de niveau 2

Simple english c01/Chemical symbols

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Chemical symbols
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Chapitre no 2
Leçon : Simple english c01
Chap. préc. :Chemical elements
Chap. suiv. :Chemical compounds
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Simple english c01/Chemical symbols
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Chemical symbols[modifier | modifier le wikicode]

Chemical elements are also given a unique chemical symbol. Chemical symbols are used all over the world. This means that, no matter which language is spoken, there is no confusion about what the symbol means. Chemical symbols of elements come from their English or Latin names. For example, carbon has the chemical symbol 'C', and sodium has chemical symbol 'Na', after the Latin natrium. Tungsten is called 'W' after its German name, wolfram.'Au' is the symbol for gold and it comes from the Latin word for gold, aurum. Another symbol which comes from Latin is 'Ag'. This is the element silver and it comes from the Latin argentum. Others were named after famous people, like einsteinium was named after Albert Einstein.

Compounds[modifier | modifier le wikicode]

Elements can join (react) to form pure compounds (such as water, salts, oxides, and organic compounds). In many cases, these compounds have a fixed composition and their own structure and properties. The properties of the compound may be very different from the elements it is made from. Sodium is a metal that burns when put into water and chlorine is a poisonous gas. When they react together they make sodium chloride (salt) which is harmless and edible.

Mixtures[modifier | modifier le wikicode]

Some elements, particularly metal elements mix together in any proportion to form new structures. Such new structures are not compounds. They are called mixtures.

Isotopes[modifier | modifier le wikicode]

Atoms of the same element, whose nuclei contain a different number of neutrons, are said to be different isotopes of the element. For example, a common isotope of the element carbon is carbon-14. It contains two more neutrons than the usual form of carbon, carbon-12, and is radioactive.

Classification[modifier | modifier le wikicode]

Elements can be classified based on physical states. At room temperature and pressure, most elements are solids, only 11 are gases and 2 are liquids.

Elements can also be classified into metals and non-metals. There are many more metals than non-metals.

However, a few elements have properties in between those of metals and non-metals. These elements are called semimetals (or metalloids).