1. Atoms Matter Lecture #2

2. I. Structure of the Atom A. There are 3 main parts the the atom (subatomic particles) 1. Proton (+): has a positive charge and is located in the nucleus of the atom mass = 1 amu (atomic mass unit) + +

3. I. Structure of the Atom A. There are 3 main parts the the atom (subatomic particles) 2. Neutron (  ): has no charge and is located in the nucleus of the atom mass = 1 amu + +  

4. I. Structure of the Atom A. There are 3 main parts the the atom (subatomic particles) 3. Electron ( - ): has a negative charge and is located spinning around the nucleus. + -   - +

5. B. The number of electrons and protons are always the same so that the electrical charge is always neutral.

6. C. Electrons whirl outside the nucleus and are about 1 / 2000 the mass of either a proton or neutron. They are located in cloudlike energy levels around the nucleus;

7. 1. The first energy level holds up to two electrons.

8. 2. The second energy level holds up to 8 electrons.

9. 3. The energy level closest to the nucleus must be filled first.

10. 4. Valence electrons are the electrons in the outermost energy level that determine how atoms BOND with other atoms. Gold has 1 valence electron

11. II.Definition of Element - Simplest type of pure substance. All known natural and man-made elements are listed in the periodic table. Web Elements