1. A primary learning objective for Biologists
The Chemistry of Life
A primary learning objective for Biologists

2. The Periodic Table of elements

3. Key Features of Arrangement:
Groups - vertical
Periods - horizontal
Atomic Number – increases from left to right down the periodic table
Number of Electrons – increases from left to right down the periodic table
Valence Electrons – outer shell

4. The Nature of Matter Atoms The basic unit of matter
Composed of subatomic particles:
Protons = positively (+) charged
Neutrons = neutral (0) charge
Together, Protons and Neutrons make the “NUCLEUS”
Electrons = negatively (-) charged
In constant motion around the nucleus; attracted to the positively charged nucleus
Same number of electrons as protons, so atoms have an overall neutral charge.

5. The Nature of Matter Elements and Isotopes
Element – a pure substance containing one type of atom
Each kind of element has the same # of Protons
Have a 1 or 2 letter symbol on the Periodic Table
Isotopes – atoms of the same element that contain different numbers of neutrons
Isotopes of an element have the same number of electrons, so their chemical properties are the same

6. The Nature of Matter Elements and Isotopes (continued)
Radioactive Isotopes – nuclei are unstable and break down over time
Uses:
Dating Rocks
Treat Cancer
Kill bacteria
“Tracers” of substances in an organism

7. The Nature of Matter Compounds
A substance formed by the chemical combination of two or more elements in definite proportions
Written as a chemical formula: examples = H2O (water), NaCl (salt)
Properties are very different from the elements that form them

8. The Nature of Matter
Bonds – the transfer or sharing of valence electrons
Ionic – bond formed when one or more electrons are transferred from one atom to another
Atoms become “ions”  negative charge if an electron is gained (anion), positive charge if an electron is lost (cation)
Covalent – bond formed when electrons are shared between atoms
Single – 2 electrons, Double – 4 electrons, Triple – 6 electrons
Molecule = the smallest unit of most compounds

9. Bond Jokes:

10. The Nature of Matter Bonds (continued)
Van der Waals = a slight attraction between oppositely charged regions of nearby molecules due to the unequal distribution of electrons in a molecule
Hydrogen bonds = attraction between hydrogen and a more electronegative element of a nearby molecule
Important in properties of water and DNA