1. Atoms, Ions and Molecules
Chemistry of Life
Atoms, Ions and Molecules

2. Atoms

3. The Atom Every element is made of atoms
All atoms of any element are the same
Atoms of different elements are different

4. Protons

7. Neutrons

11. Electrons

13. Atomic Number – Atomic Mass
Protons in Nucleus
Atomic Mass:
Sum of Masses of Protons + Neutrons
(e.g., g/mol)

14. Periodic Pattern

15. Thomson Model: The Electron
J.J. Thomson discovered electrons using an experimental device similar to your TV---over 100 years ago! He deduced the electrons must be from atoms, and there must be other, more massive particles in the atom.

16. Rutherford’s Atom Model
Mostly empty space
Small dense region-nucleus
Protons are part of nucleus
Hypothesized a third, neutral particle existed
Neutron discovered later by Chadwick

17. Bohr’s Atom & Quantum Mechanics

18. Quantum Model
Today, “the quantum model is the most realistic vision of the overall structure of the atom. It explains much of what we know about chemistry and physics” including why elements are ordered by atomic number in the Periodic Table.

19. See the Atom
Photo courtesy National Institute of Standards and Technology (NIST) STM image (7 nm x 7 nm) of a single zigzag chain of cesium atoms (red) on a gallium-arsenside surface (blue)
Photo courtesy NIST Photo source: IBM's Almaden Research Labs Atoms can be positioned on a surface using the STM tip, creating a custom pattern on the surface.

20. Fun Facts