Describing the Structure of
ATOMS
MATTER
• Anything that has volume and mass
• Everything that exists is matter, and is made of ATOMS
ATOM
• The smallest unit of an element that has all
of the properties of that element containing
a nucleus within an electron cloud.
MODEL OF THE ATOM
• A conceptual model of the atom showing a
small positively-charged nucleus surrounded
by orbiting electrons, much like the planets
orbit the Sun in our Solar System.
NUCLEUS
Positively charged
protons occupy space
within the nucleus and
cause the nucleus to
have an overall
positive charge
• The tiny, dense, positively-charged region in the
center of an atom; made up of protons and neutrons
ELECTRON CLOUD
Negatively charged
electrons occupy
the space within the
electron cloud and
cause the electron cloud
to have an
overall negative charge
• All of the area of an atom, outside the
nucleus where electrons are found
SUBATOMIC PARTICLES
(the parts that make up the Atom):
PROTON, p+
• A positivelycharged
subatomic
particle of the
nucleus of an
atom that
contributes to the
mass of the atom
SUBATOMIC PARTICLES:
(the parts that make up the Atom):
0
NEUTRON, n
• A subatomic
particle of the
nucleus of an
atom that is
without charge
that contributes to
the mass of an
atom
SUBATOMIC PARTICLES:
(the parts that make up the Atom):
ELECTRON,
e
• A negatively-charged
subatomic particle of
the electron cloud
that is involved in the
formation of
chemical bonds
ELECTRICAL CHARGE
Each electron has a
negative charge
Each proton has a positive
charge
Neutrons are without
charge
• A form of charge, designated negative, positive,
or neutral (has no charge) that is found on the
subatomic particles that make up all atoms.