There are lots of different substances but only just over a hundred elements. An element is a substance that is made up of only one kind of atom. The atoms in a particular element are the same as each ...

Students learn to classify matter as elements, compounds, and mixtures. Matter: Classification of Matter: Students learn to classify matter as elements, compounds, and mixtures and to distinguish ...

Discover the history, structure, and importance of the periodic table of elements, from Mendeleev’s discovery to modern scientific applications. When you purchase through links on our site, we may ...

If you would like to learn more about the IAEA’s work, sign up for our weekly updates containing our most important news, multimedia and more. INTERNATIONAL ATOMIC ENERGY AGENCY, The Chemical ...

A new model rectifies the long-standing deficiencies of the electronegativity concept.

Everything we can see and touch, and quite a lot that we can’t as well, is made of tiny particles called atoms. Some substances, like particles of this iron, contain only one kind of atom. Iron is an ...