Democritus was a Greek scientist who was the first to notice the existence of atoms.
Dalton was the first scientist to notice that different elements are made of different atoms, and are too small to be seen.
The atomic number tells you the date that the element was discovered.
The atomic mass number tells you how many protons + neutrons there are.
An element symbol is sometimes different letters than the name because the people didn't know how to spell.
You find the number of neutrons by subtracting the atomic number from the atomic mass number.
The period number tells you the age of the founder of the element.
The group number tells you how many electrons are in the outer most energy level.
The three element families are Metals, Non-Metals, and Metalloids, and their group numbers are 4, 7, and 13.
