|
ELEMENTS
After
reading this section you will be able to do
the following:
- Be able
to define an element.
- Be able
to recognize and recall some of the basic elements.
An
element defined
Any material that is
composed of only one type of atom is called a chemical element,
a basic element, or just an element. Any material that is composed
of more than one type of atom is called a compound. Every
element has a unique atomic structure. Scientists know of only
about 109 basic elements at this time. (This number has a habit
of changing.) All matter is composed of combinations of one or
more of these elements. Ninety-one of these basic elements occur
naturally on or in the Earth. The other elements are man-made.
You may recognize the names of some of these basic elements, such
as: hydrogen, helium, oxygen, iron, copper, gold, aluminum, uranium.
The periodic table of elements (shown below) lists the basic elements
and some of their properties.
Click on the picture for an enlarged view. (60KB)
Review
- An element
is material composed of only one kind of atom.
- A compound
is material composed of more than one kind of atom.
- Some examples
of elements that can be found on the periodic table are hydrogen,
helium, oxygen, iron, copper, gold, aluminum, uranium.
|
