Atoms and Molecules
The student will investigate and understand that all matter is made up of
atoms. Key concepts include
a) atoms are made up of electrons, protons, and neutrons;
b) atoms of any element are alike but are different from atoms of other
c) elements may be represented by chemical symbols;
d) two or more atoms may be chemically combined;
e) compounds may be represented by chemical formulas;
f) chemical equations can be used to model chemical changes; and
g) a limited number of elements comprise the largest portion of the solid
Earth, living matter, the oceans, and the atmosphere.
The Typical Atom - Protons,
- The basic structural components of the typical
atom are electrons,
protons, and neutrons.
Protons and neutrons comprise the
nucleus of an atom.
- An element is a form of matter made up of
one type of atom. The atoms of an element are
basically alike, though the number of neutrons may
- The atoms of one element and another
element differ in the number of protons.
- A limited number of elements, including, silicon,
aluminum, iron, sodium, calcium, potassium, magnesium, hydrogen, oxygen,
nitrogen, and carbon form the largest portion of the
Earth’s crust, living matter, the oceans, and
- Two or more atoms of different elements
may combine to form a compound.
- Compounds can be represented by chemical formulas.
Each different element in the compound is represented by its
- The number of each type of element in the compound (other than 1) is
represented by a small number (the subscript)
to the right of the element symbol. (identify the name and number
of each element - O2, H2O,
CO2, or CaCO3.)
Chemical Equations show Chemical
- Chemical equations can be used to model
chemical changes illustrating how elements
become rearranged in a chemical reaction.
(Distinguish the types of elements and number of each element in the
chemical equation - students don't need to know how to balance