I. The Atom is the smalles unit of an Element

A. there are 3 major parts to an Atom

1. proton=positive electrical charge

2. electron=negative electrical charge

3. neutron=neutral electrical charge

B. made of positive protons and neutral neutrons

C. The mass of an atom depends on how many protons and neutrons

1. the Mass number is the sum of protons and neutrons

D. The electrons have different energies

1. The lower the energy, the more likely it will be to be found near the nucleus

E. Ions = atoms that have gained or lost electrons and are no longer electrically neutral

1. Ionic Compounds are formed when a negative ion form with a positive ion to form a neutral compound

F. Mixtures are formed when different substances combine but still keep their own properties

E. Solutions are formed when 2 or more substances one of which is dissolved in the other