Name: Teacher: Pd.
Date:
TEK 8.5A: Atomic Structure
TEK 8.5A: Describe the structure of atoms, including the masses, electrical
charges, and locations, of protons and neutrons in the nucleus and
electrons in the electron cloud.
Atomic Structure
• Atoms are the smallest particle of an element. Each element is made of only one
kind of atom. For example, gold is only made of gold atoms and neon is only made
of neon atoms. The overall shape of all atoms is spherical (like a basketball), but
they vary in size.
• Each atom has a nucleus located at its center, surrounded by an electron cloud,
which is mostly empty space outside of the nucleus. The nucleus is very small,
compared with the overall size of the atom. In the Electron Cloud Model of the
atom shown below, both the nucleus and the sub-atomic particles are shown much
larger than they really are—they otherwise would be invisible at this scale.
Protons -
7 total
+
+
Ø
Ø
Electron Cloud
Ø
+ +
+
+ Ø Ø
Ø
+
Nucleus
Neutrons -
7 total
Electrons (-) 7 total
Electron Cloud Model of a Nitrogen Atom
• Atoms are made of three different kinds of sub-atomic particles: protons,
neutrons, and electrons.
• All of an atom’s protons and neutrons are tightly packed together in the atom’s
nucleus. The nucleus is held together by the strong nuclear force, which is
stronger than the electromagnetic force that otherwise would cause like-charged
protons to repel one another.
• Protons have a positive (+) charge, and each has a mass of one “atomic mass
unit” (amu).
Ø
