Metals, nonmetals, and metalloids are the three main classes of chemical elements. Metals are good conductors of heat and electricity and are malleable and ductile. Nonmetals are usually poor conductors and are not malleable or ductile, with many being gases at room temperature. Metalloids have properties between metals and nonmetals, and some can conduct electricity under certain circumstances. The document also defines key terms related to elements like atomic number, chemical symbol, and atomic mass.

1. LESSON 3:
METALS, NONMETALS, &
METALLOIDS

2. CHEMICAL
ELEMENT, ALSO
CALLED ELEMENT,
ANY SUBSTANCE
THAT CANNOT BE
DECOMPOSED
INTO SIMPLER
SUBSTANCES BY
ORDINARY
CHEMICAL
PROCESSES.
ELEMENTS ARE
THE
FUNDAMENTAL
MATERIALS OF
WHICH ALL
MATTER IS
COMPOSED.

3. Atomic Number
the number of protons in the
nucleus of an atom, which
determines the chemical
properties of an element and its
place in the periodic table.

4. Chemical Symbol
A chemical symbol is a one- or
two-letter designation of an
element. The first letter of a
symbol is always capitalized. If the
symbol contains two letters, the
second letter is lower case.

5. Element's Name
New elements can be named after
a mythological concept, a mineral,
a place or country, a property or a
scientist. The names have to be
unique and maintain "historical
and chemical consistency".

6. Atomic Mass
the mass of an atom of a chemical
element expressed in atomic mass
units. It is approximately
equivalent to the number of
protons and neutrons in the atom
(the mass number)

7. The elements can be classified as metals,
nonmetals, or metalloids. Metals are good
conductors of heat and electricity, and are
malleable (they can be hammered into
sheets) and ductile (they can be drawn into
wire). Most of the metals are solids at room
temperature, with a characteristic silvery
shine (except for mercury, which is a liquid).
Metals, Non
Metals, &
Metalloids

8. Metals, Non
Metals, &
Metalloids
Nonmetals are (usually) poor conductors of heat
and electricity, and are not malleable or ductile;
many elemental nonmetals are gases at room
temperature, while others are liquids and solids.
The metalloids are intermediate in their properties.
In their physical properties, they are more like
nonmetals, but under certain circumstances,
several can be made to conduct electricity. These
semiconductors are essential in computers and
other electronic devices.

9. WHERE CAN WE FIND THEM?