READER'S GUIDE

Many young people like to play with Lego blocks, tinker-toys, erector sets, and similar building games. It's fun to see how many different ways a few simple shapes can be put together.

The same can be said of chemistry. The world is filled with an untold number of different objects, ranging from crystals and snowflakes to plant and animal cells to plastics and medicines. Yet all of those objects are made from various combinations of only about 100 basic materials: the chemical elements.

Scientists have been intrigued about the idea of an "element" for more than two thousand years. The early Greeks developed complicated schemes that explained everything in nature using only a few basic materials, such as earth, air, fire, and water. The Greeks were wrong in terms of the materials they believed to be "elemental." But they were on the right track in developing the concept that such materials did exist.

By the 1600s, chemists were just beginning to develop a modern definition of an element. An element, they said, was any object that cannot be reduced to some simpler form of matter. Over the next 300 years, research showed that about 100 such materials exist. These materials range from such well known elements as oxygen, hydrogen, iron, gold, and silver to substances that are not at all well known, elements such as neodymium, terbium, rhenium, and seaborgium.

By the mid-1800s, the search for new chemical elements had created a new problem. About 50 elements were known at the time. But no one yet knew how these different elements related to each other, if they did at all. Then, in one of the great coincidences in chemical history, that question was answered independently by two scientists at almost the same time, German chemist Lothar Meyer and Russian chemist Dmitri Mendeleev. (Meyer, however, did not publish his research until 1870, nor did he predict the existence of undiscovered elements as Mendeleev did.)

Meyer and Mendeleev discovered that the elements could be grouped together to make them easier to study. The grouping occurred naturally when the elements were laid out in order, according to their atomic weight. Atomic weight is a quantity indicating atomic mass that tells how much matter there is in an element or how dense it is. The product of Meyer and Mendeleev's research is one of the most famous visual aids in all of science, the periodic table. Nearly every classroom has a copy of this table. It lists all of the known chemical elements, arranged in rows and columns. The elements that lie within a single column or a single row all have characteristics that relate to each other. Chemists and students of chemistry use the periodic table to better understand individual elements and the way the elements are similar to and different from each other.

About Chemical Elements: From Carbon to Krypton

Chemical Elements: From Carbon to Krypton is designed as an introduction to the chemical elements. Elements with atomic numbers 1 through 100 are examined in separate entries, while the transfermium elements (elements 101 through 112) are covered in one entry.

Students will find Chemical Elements useful in a number of ways. First, it is a valuable source of fundamental information for research reports, science fair projects, classroom demonstrations, and other activities. Second, it can be used to provide more detail about elements and compounds that are only mentioned in other science textbooks or classrooms. Third, it will be an interesting source of information about the building blocks of nature for those who simply want to know more about the elements.

The three-volume set is arranged alphabetically by element name. Each entry contains basic information about the element discussed: its discovery and naming, physical and chemical properties, isotopes, occurrence in nature, methods of extraction, important compounds and uses, and health effects.

The first page of each entry provides basic information about the chemical element: its chemical symbol, atomic number, atomic mass, family, and pronunciation. A diagram of an atom of the element is also shown, with the atom's electrons arranged in various "energy levels" outside the nucleus. Inside the nucleus, the number of protons and neutrons is indicated.

Entries are easy to read and written in a straightforward style. Difficult words are defined within the text. Each entry also includes a "Words to Know" section that defines technical words and scientific terms. This enables students to learn vocabulary appropriate to chemistry without having to consult other sources for definitions.

Added features

Chemical Elements: From Carbon to Krypton includes a number of additional features that help make the connection between elements, minerals, the people who discovered and worked with them, and common uses of the elements.

• Three tables of contents: alphabetically by element name; by atomic number; and by family group provide varied access to the elements.
• A timeline at the beginning of each volume provides a chronology of the discovery of the elements.
• Nearly 200 photographs and illustrations of the elements and products in which they are used bring the elements to life.
• Sidebars provide fascinating supplemental information about scientists, theories, uses of elements, and more.
• Interesting facts about the elements are highlighted in the margins.
• Extensive cross references make it easy to read about related elements. Other elements mentioned within an element's entry are boldfaced upon first mention, serving as a helpful reminder that separate entries are written for these elements.
• A list of sources for further reading for some elements and for general chemistry is found at the end of each volume.
• A comprehensive index quickly points readers to the elements, minerals, and people mentioned in Chemical Elements: From Carbon to Krypton.
• A periodic table on the endsheets gives students a quick look at the elements.

Special thanks

The editor wishes to thank imaging guru Randy Bassett for his patience and guidance. Thanks also to Bernard Grunow for his informal assistance in the early stages of the editing phase. Kudos to typesetter Marco Di Vita, who, as always, is in a league by himself. And, finally, a big-time thank-you to soul-mate Beth Baker, whose editorial toolbelt, no doubt, needs some duct tape by now.

Comments and suggestions

We welcome your comments on this work as well as suggestions for future science titles. Please write: Editors, Chemical Elements: From Carbon to Krypton, U○X○L, 27500 Drake Rd., Farmington Hills, Michigan, 48331-3535; call toll-free: 800-347-4253; send fax to 248-699-8066; or send e-mail via http://www.gale.com.