Atoms, Molecules and Ions

Chapter 2
Atoms,
Molecules
and Ions




Ms Veronique Joubert

,Learning Outcomes...
 Introduction to the Periodic Table.
 Describe the Atomic Theory and Dalton’s Postulates of atoms.
 Identify the subatomic particles in an atom and the difference between
the atomic number and the mass number.
 Define isotopes of an element and determine the average atomic mass
of an atom.
 Distinguish between the formation of different molecules and
compounds.
 Understand the formation of ions and predicting the charges of ions.

Department of Chemistry

,The Periodic Table

, Introduction to the Periodic Table (PT)
Dmitri Mendeleev (1869, Russian)
- Organized elements by increasing atomic mass.

- Elements with similar properties were grouped
together.

- Predicted properties of undiscovered elements.




Henry Mosely (1913, British)
- Organized elements by increasing atomic number.

Department of Chemistry