Time again for our Website of the Week, when we showcase interesting and innovative online destinations. Our web guide is VOA's Art Chimes.

This week, we feature an online version of one of the most useful tools for understanding chemistry and the chemical elements that make up the world around us.

The Periodic Table of the Elements has been around, in one form or another, since the mid-19th century. Russian chemist Dmitri Mendeleev is generally credited with creating the first version. But it's been modified over the years, first on paper and now online in various versions, including the one hosted at Los Alamos National Laboratory, periodic.lanl.gov.

JOHN: "The table itself is arranged in increasing number of atomic number. It's also arranged according to just general chemical properties. For instance all the Noble gases are on the right-hand side of the Periodic Table. So it's a very useful tool for chemists. It's essentially a chessboard and the rulebook for chess all-in-one for chemists."

Like any Periodic Table, this one features the chemical symbol, atomic weight, and atomic number for each of the known elements. But there's more: Los Alamos chemist Kevin John says this online Periodic Table offers in-depth information about each element, as well.

JOHN: "If you click on a given element, it has the history related to its discovery, various properties, uses and costs of the element. And in addition it also has some handling information, if the element itself is toxic. So I think there's a lot of embedded information in the webpage that one wouldn't be able to get on a hard copy."

Although this version was designed for students up through high school age, Kevin John says he refers to the Periodic Table daily in his work creating medical isotopes.

JOHN: "You know, I can't remember every single weight of every element and as part of my job I need to consult that from time to time in a laboratory environment. I still use it every day."

For added value, Los Alamos National Laboratory has also included articles on how to use the periodic table, how elements get their names, and more.

The Periodic Table of the Elements, online at periodic.lanl.gov, or get the link from our site, voanews.com.