The periodic table of elements—also known as Mendeleev’s table—was developed in 1869 by Russian chemist Dmitri Mendeleev. It organizes all known chemical elements by their atomic number ...

When you enter the laboratory, you will find a table on the wall in the shape of the periodic table. However, instead of the element, there are numbers in certain squares of the table. While it is ...

The atomic number of an atom determines which element it is. An element with 17 protons will always be chlorine. However the mass number of the element can vary, which means that it can have ...

Creative Commons (CC): This is a Creative Commons license. Attribution (BY): Credit must be given to the creator. The presence of iron and manganese in drinking water distribution systems can ...

Beryllium is a highly toxic metal so it is not of great practical value and is not researched a great deal. But since it has a low molecular weight it is useful as a window in x-ray spectrometers ...

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