Atoms

Cliff Notes

I. The Atom

A. atom: the smallest unit of an element that keeps the properties of that element

1. "atom" comes from the Greek word "atomos" which means "not able to be divided"

B. a single penny has 20,000,000,000,000,000,000,000 atoms in it

II. Inside the Atom

A. all atoms are made of the same 3 subatomic (smaller than an atom) particles:

-protons, neutrons, electrons

B. nucleus: the positively charged center of the atom

C. Inside the nucleus are protons (+ charge) and neutrons (neutral charge)

-protons weigh exactly one atomic mass unit (AMU)

-neutrons weigh approximately 1 AMU as well

D. Outside the nucleus are electrons (- charge) moving around in an electron cloud

-electrons weigh approximately 0 AMU (basically nothing because they're so small)