![]() They are not particularly malleable, and whereas most metals are shiny, nonmetals may be dull-colored, black (in the case of carbon in some forms or allotropes), or invisible, as is the case with most of the gaseous nonmetals. They are poor conductors of heat and electricity (though carbon, a good electrical conductor, is an exception), and they tend to form negative ions by gaining electrons. In general, the nonmetals are characterized by properties opposite those of metals. All gaseous elements are nonmetals, a group that also includes some solids, as well as bromine, the only element other than mercury that is liquid at room temperature. With the exception of hydrogen, placed in Group 1 above the alkali metals, the nonmetals fill a triangle-shaped space in the upper right corner of the periodic table. The vast majority of elements -87 in all -are metals, and these occupy the left, center, and part of the right-hand side of the periodic table. They are excellent conductors of heat and electricity, and tend to form positive ions by losing electrons. Metals are ductile, or malleable, meaning that they can be molded into different shapes without breaking. The majority of elements on the periodic table are metals: solids (along with one liquid, mercury) which are lustrous or shiny in appearance. Among the other "orphan" nonmetals are phosphorus and sulfur, the "brimstone" of the Bible, as well as boron and selenium. Indeed, much of life -human, animal, and plant -can be summed up with these four elements, which together make Earth different from any other known planet. Hydrogen and helium, a nonmetal of the noble gas family, together account for about 99% of the mass of the universe, while Earth and the human body are composed primarily of oxygen, with important components of carbon, nitrogen, and hydrogen. Two more, addressed in this essay, are absolutely essential to human life: oxygen and nitrogen. ![]() Two of these eight -hydrogen and carbon -are so important that separate essays are devoted to them. Included in this broad grouping are the six noble gases, the five halogens, and eight "orphan" elements. Generally, they are poor conductors of heat and electricity, and they are not ductile: in other words, they cannot be easily reshaped. Nonmetals, as their name implies, are elements that display properties quite different from those of metals.
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