Atom and Subatomic Paricles

Activity: Cutting Up a Post-it Note

To begin, let's think about how
small we can make something by cutting it into smaller and smaller pieces.

Atoms: The Building
Blocks of Matter

Everything you see around you
is made up of atoms. These are
the smallest units of matter that
still have the properties of an
element.

Subatomic Particles:
Even Smaller than
Atoms

Atoms are not the smallest
particles. They are made up of
even smaller particles: protons,
neutrons, and electrons.

Protons, Neutrons, and Electrons

● Protons have a positive

charge and are found in
the nucleus.

● Neutrons have no charge

and are also in the
nucleus.

● Electrons have a

negative charge and orbit
the nucleus.

Valence Electrons and
Electron Shells

Electrons are found in energy
levels or shells around the
nucleus. The first shell can hold
up to 2 electrons, the second up
to 8, and the third up to 18.

2 X 8 X 18

Atomic Number and Atomic Mass

The atomic number of an
element tells us the
number of protons in the
nucleus. The atomic mass
is the sum of protons and
neutrons.

Different Atoms, Different Elements

Not all atoms are the same.
Different elements have
different numbers of protons,
neutrons, and electrons,
which determine their
properties and the things
they make up.

Neutrons and Atomic
Stability

We can determine the number
of neutrons by subtracting the
atomic number from the atomic
mass. The balance between
protons and neutrons affects
the atom's stability.