Metals - How it works

General Properties of Metals

Metals are lustrous or shiny in appearance, and malleable or ductile, meaning that they can be molded into different shapes without breaking. Despite their ductility, metals are extremely durable and have high melting and boiling points. They are excellent conductors of heat and electricity, and tend to form positive ions by losing electrons.

The bonds that metals form with each other, or with nonmetals, are known as ionic bonds, which are the strongest type of chemical bond. Even within a metal, however, there are extremely strong bonds. Therefore, though it is easy to shape metals (that is, to slide the atoms in a metal past one another), it is very difficult to separate metal atoms. Their internal bonding is thus very strong, but nondirectional.

Internal bonding in metals is described by the electron sea model, which depicts metal atoms as floating in a "sea" of valence electrons, the electrons involved in bonding. These valence electrons are highly mobile within the crystalline structure of the metal, and this mobility helps to explain metals' high conductivity. The ease with which metal crystals allow themselves to be rearranged explains not only metals' ductility, but also their ability to form alloys, a mixture containing one or more metals.

Abundance of Metals

Metals constitute a significant portion of the elements found in Earth's crust, waters, and atmosphere.

The following list shows the most abundant metals on Earth, with their ranking among all elements in terms of abundance. Many other metals are present in smaller, though still significant, quantities.

• 3. Aluminum (7.5%)
• 4. Iron (4.71%)
• 5. Calcium (3.39%)
• 6. Sodium (2.63%)
• 7. Potassium (2.4%)
• 8. Magnesium (1.93%)
  

  A LUMINUM IS THE MOST ABUNDANT METAL ON E ARTH . T HIS PHOTO SHOWS THE FIRST BLOBS OF ALUMINUM EVER ISOLATED , A FEAT PERFORMED BY C HARLES H ALL IN 1886. (

  James L. Amos/Corbis

  . Reproduced by permission.)
• 10. Titanium (0.58%)
• 13. Manganese (0.09%)

In addition, metals are also important components of the human body. The following list shows the ranking of the most abundant metals among the elements in the body, along with the percentage that each constitutes. As with the quantities of metals on Earth, other metals are present in much smaller, but still critical, amounts.

• 5. Calcium (1.4%)
• 7. Magnesium (0.50%)
• 8. Potassium (0.34%)
• 10. Sodium (0.14%)
• 12. Iron (0.004%)
• 13. Zinc (0.003%)

Metals on the Periodic Table

On the periodic table of elements, metals fill the left, center, and part of the right-hand side of the chart. The remainder of the right-hand section is taken by nonmetals, which have properties quite different from (and often opposite to) those of metals, as well as metalloids, which display characteristics both of metals and nonmetals. Non-metallic elements are covered in essays on Non-metals; Metalloids; Halogens; Noble Gases; and Carbon. In addition, hydrogen, the one nonmetal on the left side of the periodic table—first among the elements, in the upper left corner—is also discussed in its own essay.

The total number of metals on the periodic table is 87—in other words, about 80% of all known elements. These include the six alkali metals, which occupy Group 1 of the periodic table, as well as the six alkaline earth metals, or Group 2. To the right of these are the 40 transition metals, whose groups are unnumbered in the North American version of the periodic table. Among the transition metals are two elements, lanthanum and actinium, often lumped in with the families of inner transition metals that exhibit similar properties. These are, respectively, the 14 lanthanides and 14 actinides. In addition, there are the seven "orphan" metals of periods 3 through 5, mentioned in the introduction to this essay, which will be discussed below.

The various families of elements are defined, not so much by external characteristics as by the configurations of valence electrons in their atoms' shells. This subject will not be discussed in any depth here; instead, the reader is encouraged to consult essays on the specific metal families, which discuss the electron configurations of each.