Skip to main content Skip to Search Box

element

From The Columbia Encyclopedia
in chemistry, a substance that cannot be decomposed into simpler substances by chemical means. A substance such as a compound can be decomposed into its constituent elements by means of a chemical reaction, but no further simplification can be achieved. An element can, however, be decomposed into simpler substances, such as protons and neutrons or various combinations of them, by the methods of particle physics, e.g., by bombardment of the nucleus. The smallest unit of a chemical element that has the properties of that element is called an atom . Many elements (e.g., helium) occur as single atoms. Other elements occur as molecules made up of more than one atom. Elements that ordinarily occur as diatomic molecules include hydrogen, nitrogen, oxygen, and the halogens, but oxygen also occurs as a triatomic form called ozone. Phosphorus usually occurs as a tetratomic molecule, and crystalline sulfur occurs as molecules containing eight atoms. Atomic Number and Mass Number Regardless of how…
18,456 results

Full text Article element

From Astronomy Encyclopedia
Substance that cannot be broken down into simpler substances by chemical means. An element is composed solely of ATOMS with identical atomic numbers (that is, they all have the same number of protons within their nuclei), but it may contain a number of different ISOTOPES . So far 107 elements have…
| 319 words
Key concepts:

Full text Article element

From The Hutchinson Unabridged Encyclopedia with Atlas and Weather Guide
Substance that cannot be split chemically into simpler substances. The atoms of a particular element all have the same number of protons in their nuclei (their proton or atomic number ). Elements are classified in the periodic table of the elements . Of the known elements, 92 are known to occur…
| 645 words
Key concepts:

Full text Article element

From Hawley's Condensed Chemical Dictionary
One of the 112 presently known kinds of substances that compose all matter at and above the atomic level. According to a theory that has gained acceptance, the lightest elements were formed in less than half an hour from a primordial complex called ylem, a mixture of neutrons and electromagnetic…
| 340 words
Key concepts:

Full text Article element

From The American Heritage(R) Dictionary of the English Language
A fundamental, essential, or irreducible constituent of a composite entity. elements The basic assumptions or principles of a subject. Mathematics a. A member of a set. b. A point, line, or plane. c. A part of a geometric configuration, such as an angle in a triangle. d. …
| 339 words
Key concepts:

Full text Article element

From The American Heritage Student Science Dictionary
A substance that cannot be broken down into simpler substances by chemical means. An element is composed of atoms that have the same atomic number; that is, each atom has the same number of protons in its nucleus as all other atoms of that element. Today 118 elements are known, of which 92 are known…
| 254 words
Key concepts:

Full text Article element

From Collins English Dictionary
n 1 any of the 118 known substances (of which 93 occur naturally) that consist of atoms with the same number of protons in their nuclei Compare compound1(sense 1) 2 one of the fundamental or irreducible components making up a whole 3 a cause that contributes to a result; factor 4 any group that is…
| 339 words
Key concepts:

Full text Article element

From The Columbia Encyclopedia
in chemistry, a substance that cannot be decomposed into simpler substances by chemical means. A substance such as a compound can be decomposed into its constituent elements by means of a chemical reaction, but no further simplification can be achieved. An element can, however, be decomposed into…
| 2,204 words
Key concepts:

Full text Article Element

From Brewer's Dictionary of Phrase and Fable
In ancient and medieval philosophy, earth, air, fire and water were the four elements from which all other substances were composed. This conception was introduced by empedocles in the 5th century  bc . Later a fifth immaterial element was added, called the quintessence or quinta essentia , supposed…
| 188 words
Key concepts:

Full text Article element

From The Chambers Dictionary
a first principle; one of the essential parts of anything; an ingredient; a small amount; the proper medium, habitat or sphere of any thing or being; any one of the four substances, fire, air, earth and water, supposed by the ancients to be the foundation of everything (in China a fifth, wood, was…
| 310 words
Key concepts:

Full text Article element

From Collins Dictionary of Astronomy
Any of a large number of substances, including hydrogen , helium , carbon, nitrogen, oxygen, and iron, that consist entirely of atoms of the same atomic number , i.e. with the same number of protons in their nuclei. The atoms are not all identical however: isotopes of an element can occur with…
| 205 words
Key concepts:
Mind Map

Stack overflow
More Library Resources