| NSES Content Standard B
Physical Science: Structure and properties of matter Grades 9-12, page 179 Bonds between atoms are created when electrons are paired up by being
transferred or shared. A substance composed of a single kind of atom is
called an element. The atoms may be bonded together into molecules or crystalline
solids. A compound is formed when two or more kinds of atoms bind together
chemically.
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Benchmark 4D The Physical Setting: Structure
of Matter
Grades 6-8, page 78
Scientific ideas about elements were borrowed from some Greek philosophers
of 2,000 years earlier, who believed that everything was made from four
basic substances: air, earth, fire, and water. It was the combinations
of these "elements" in different proportions that gave other substances
their observable properties. The Greeks were wrong about those four, but
now over 100 different elements have been identified, some rare and some
plentiful, out of which everything is made. Because most elements tend
to combine with others, few elements are found in their pure form.
Benchmark 4D The Physical Setting: Structure
of Matter
Grades 9-12, page 80
Atoms are made of a positive nucleus surrounded by negative electrons.
An atom's electron configuration, particularly the outermost electrons,
determines how the atom can interact with other atoms. Atoms form bonds
to other atoms by transferring or sharing electrons.
Benchmark 4D The Physical Setting: Structure
of Matter
Grades 9-12, page 80
Atoms often join with one another in various combinations in distinct
molecules or in repeating three-dimensional crystal patterns. An enormous
variety of biological, chemical, and physical phenomena can be explained
by changes in the arrangement and motion of atoms and molecules.