Although there are millions of known substances, there are only about 100 elements. An element is a substance that cannot be broken down into simpler substances. Imagine cutting a copper (Cu) wire into smaller and smaller pieces. Eventually you would end up with extremely tiny particles called copper atoms. An atom is the smallest particle of an element. An element has a fixed composition because it contains only one type of atom. No two elements contain the same type of atom.
Examples of elementsEdit
At room termperature (20°C, or 68°F), most elements are solids, including the elements aluminum (Al) and carbon (C). You have seen aluminum foil used to wrap food. Most soft drink cans are ade from aluminum. Carbon is the main element in the marks you make with a pencil on a piece of paper. Some elements are gases at room temperature. The elements oxygen (O) and nitrogen (N) are the main gases in the air you breathe. Only two elements are liquids at room temperature, bromine (Br) and mercury (Hg), both of which are extremely poisonous.
Symbols for elementsEdit
In 1813, Jöns Berzelius, a Swedish chemist, suggested that chemists use symbols to represent elements. Many of the symbol he assigned to the elements are still used. Each symbol has either one or two letters. The first letter is always capitalized. If there is a second letter, it is not captialized.
It is easy to see why C and Al are used to represent carbon and aluminum. But why does gold have the symbol Au? The symbols that Berzelius chose were based on the Latin names of the elements. The Latin name for gold is aurum.
The symbols allow scientists who speak different languages to communicate without confusion. For example, nitrogen is known as azote in France, as stickstoff in Germany, and as nitrógeno in Mexico. But scientists who shpeak English, French, German, and Spanish all agree that the symbol for the element nitrogen is N.
Sometimes an element's name contains a clue to its properties. For example, the name hydrogen (H) comes from the Greek words hydro and genes, meaning "water" and "forming".