Transcript How Atoms Differ (Section 4.3) part 1

Bellringer
1. Who is credited with the development of
the periodic table?
2. What is the difference between
Mendeleev’s version of the periodic table
and the current version of the periodic
table?
How Atoms Differ
Objectives:
3.2 Calculating the number of protons,
neutrons, and electrons in an isotope
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:
– Hydrogen?
– Lead?
– Chlorine?
Atomic Number (cont.)
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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?
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?
Practice & Assignment
• P.99: 11-13
• Study Guide workbook: p.21 (1-12)