Parts of an Atom

First off, what is an atom? Atoms are the smallest parts to which an element can be divided yet still be that element. Atoms are the building blocks of all matter.

How small is an atom? An atom is so small that a penny contains about 2 x 1022 or 20,000,000,000,000,000,000,000 atoms!!!

But there’s more… Atoms consist of even smaller particles. These include: Protons Neutrons Electrons

Parts of an Atom The protons and neutrons make up the center or nucleus.

The Nucleus The center of an atom Small, dense (packed tightly) Contains protons and neutrons: most of the atom’s mass So dense, if it were the size of a grape, it would weigh over 9 million tons!

Protons Located in the nucleus Positive charge (+) Mass of 1 atomic mass unit (amu) protons = positive

Have no charge - neutral Mass of 1 amu Neutrons Located in the nucleus Have no charge - neutral Mass of 1 amu neutrons = neutral

Electrons Found outside of the nucleus in electron clouds (think of rings around a target) Negatively charged (-) Mass of almost zero Number of electrons equals the numbers of protons to cancel out the charges (think of -1+1=0) electrons = negative

Review: Parts of an Atom Charge Location Mass Proton Positive (+) Nucleus 1 amu Neutron No charge Electron Negative (-) Electron Clouds Almost zero