1. Atom Notes
Atom – small particle that makes up most types of matter (One million atoms lined up equals the thickness of one human hair)
Atomic structure
Nucleus – central part of an atom
Protons – positively charged particles in the nucleus of an atom
Neutrons – uncharged particles in the nucleus of an atom
Electrons - negatively charged particles in an atom

2. Atom

3. History of Atomic Theory
Dalton – (atomic model) Theory that substances were made of atoms, small, hard, dense spheres that could not be created, destroyed, or altered.
Dalton’s model of the atom
John Dalton

4. History of Atomic Theory
Thomson – (discovering the electron) Proposed that atoms were made up of smaller particles. Theory that smaller negatively charged particles are spread evenly around a positively charged nucleus. His model was called the plum-pudding model.

5. History of Atomic Theory
Rutherford – (the nucleus) Proposed that atoms had a dense, positively charged nucleus surrounded by electrons.
Chadwick – discovered the neutrons
Rutherford’s model

6. History of Atomic Theory
Bohr – Said that electrons revolve around the nucleus in circular paths or orbits and that electrons could only exist in certain orbits and at certain energy levels.
nitrogen
Example of Bohr’s model of the atom

7. Periodic Table
Mendeleev – arranged 63 elements into groups based on their chemical properties and atomic weights.

9. Periodic Table Element name Atomic number Symbol State of matter
Atomic mass
Hydrogen 1 H
1.008

10. Element Information For any element: Number of Protons = Atomic Number
Number of Electrons = Number of Protons = Atomic Number
Number of Neutrons = Mass Number - Atomic Number
Mass number = Protons + Neutrons (not found on periodic table)

11. Isotopes
Isotopes have the same number of protons but a different mass number.
Example: Carbon – and Carbon –14
Average atomic mass is an average of all the isotopes (can be found on the periodic table)

12. Draw atoms
Shell #
# of electrons
in shell 1 2 8 3 18 4 32 5

13. Metal, Nonmetal, Metalloid
Metals – good conductors -malleable and ductile -lose electrons
Nonmetals – poor conductors -brittle -gain electrons -form covalent bonds
Metalloids – show properties of both metals and nonmetals.