1. Bellringer Who is credited with the development of the periodic table?
What is the difference between Mendeleev’s version of the periodic table and the current version of the periodic table?

2. How Atoms Differ Objectives:
3.2 Calculating the number of protons, neutrons, and electrons in an isotope

3. Atomic Number Def.: the number of PROTONS in an atom
What is the atomic number of:
Hydrogen?
Lead?
Chlorine?
How many protons are in an atom of:

4. Atomic Number (cont.) What is the charge of a proton?
Where are protons found?
What else is in the nucleus?
What would be the charge of the NUCLEUS of the following elements:
Hydrogen?
Lead?
Chlorine?

5. Atomic Number (cont.)
What is needed to BALANCE this positive nuclear charge, so the atom is neutral?
So how many electrons
Atomic number = number of protons = number of electrons
How many electons are in an atom of:
Hydrogen?
Lead?
Chlorine?

6. Practice & Assignment
P.99: 11-13
Study Guide workbook: p.21 (1-12)