1. The Chemistry of Life
The Nature of Matter

2. Chemistry Life depends on chemistry.
The study of chemistry begins with the basic unit of matter, the atom.

3. Atom The atom is made up of three subatomic particles: Protons
Neutrons
Electrons

4. Protons and Neutrons Protons are positively charged particles.
Neutrons carry no charge.
Strong forces bind protons and neutrons together to form the nucleus, which is at the center of the atom.

5. Electrons Electrons are negatively charged particles.
Electrons are found in a cloud outside of the nucleus. We describe them as being in shells.
Because atoms are neutral, the number of electrons equal the number of protons.

6. Electron Shells First shell: called K – 2 electrons
Second shell: called L – 8 electrons
Third shell: called M – 18 electrons
Fourth shell: called N – 32 electrons
Fifth shell: called O – 50 electrons

7. Elements
A chemical element is a pure substance that consists entirely of one type of atom.
92 Elements exist naturally.
We classify elements based on electrons in the outer shell, and organize them into a chart called the Periodic Table of Elements.

8. The Periodic Table of Elements

9. Reading the PToE
Element Symbol
Element Name 6 C
Carbon
12.011

10. Reading the PToE Atomic Number: the number of protons in the atom. 6
Mass Number: the sum of the protons and neutrons in the nucleus
Atomic Mass: the average of the mass of the isotopes 6 C
Carbon
12.011

11. Isotopes
Atoms of the same elements that differ in the number of neutrons they contain are known as isotopes.
Because the have the same number of electrons, all isotopes of an element had the same chemical properties.

12. Isotopes of Carbon

13. The Atom’s Family e e e
Nucleus
Electron
Shells e e e