CHAPTER+FOUR-ATOMS+AND+ELEMENTS+CONT>>


 * An Atom is made up of protons, neutrons, and electrons**__:__** the proton and the electron both have an electrical charge.
 * protons are + charge, electrons are - negative
 * The number of protons in the nucleus of an atom is the **atomic number**.


 * __Classifying metals nonmetals and metalloids__**



Aside from the elements being able to be divided as metals non metals and metalloids they can also be broadly divided into the:
 * Group 1A/Alkali Metals-very reactive: **+1 charge**
 * Group 2A/Alkaline Earth Metals-fairly reactive:+**2 charge**
 * Transition elements:Groups 3-12 differentw/exceptions
 * Group 17-Halogens **-1 charge**
 * Exceptions:**

Br, Al: **+3 charge**

N, P **:-3 charge** O, S**: -2 charge**


 * Group 18/Noble Gases-chemically stable, no charge

**Isotopes: When the number of neutrons varies**
isotopes are atoms with the same number of protons but different numbers of neutrons. Chapter 5 Molecules and compounds CONT>>>**
 * percent natural abundance: the relative amounts of each different isotope present in a naturally occuring sample.
 * Atomic mass=(Fraction of isotope 1 x Mass of isotope 1) + (Fraction of isotope 2 x Mass of isotope 2) +...