The Basics of Chemistry Text pages 20 – 24. To play the movies and simulations included, view the presentation in Slide Show Mode.

Elements, Molecules, and Compounds The atom is the smallest unit of matter. Atoms contain protons, neutrons and electrons ELEMENT – pure substance containing 1 type of atom example: Hydrogen H MOLECULE – combination of 2 or more atoms example: Oxygen O2 COMPOUND – Molecules that contain different atoms Water H2O Carbon dioxide CO2

The Periodic Table You can tell two important things from the column number of an element. Column 1  1 outer electron, forms a 1+ charge Column 2  2 outer electrons, forms a 2+ charge Column 3  3 outer electron, forms a 3+ charge Column 4  4 outer electrons, no charge, covalent bonding Column 5  5 outer electron, forms a 3- charge Column 6  6 outer electrons, forms a 2- charge Column 7  7 outer electron, forms a 1- charge Column 8  8 outer electrons, neutral, no charge The middle section of transition metals fits here. It is NOT important for our biology lesson.

Remember Bohr Diagrams? Hydrogen – H Atomic Number = 1, 1 proton, 1 electron 1 electron shell   Helium Atom He Atomic Number = 2, 2 protons, 2 electrons 

8 Bohr Diagrams How many electrons can fit in the first shell? 2 The second shell? 8 The third?

C What is the symbol for carbon? Let’s Try A Few Try and draw the Bohr diagram for carbon in your binder. C

Bohr Diagrams - Carbon Let’s try a few more examples …

Chemical Bonding How are atoms held together? Chemical Bonds There are two types of chemical bonds: Ionic Bonding - one atom donates an electron to another atom positive ion (lost electrons) negative ion (gained electrons) Covalent Bonding - involves sharing electrons between atoms

What is an Ion? Table Salt End result NaCl Ion is an atom that becomes electrically charged by gaining or losing an electron… Example: Table Salt End result NaCl Sodium ATOM Chlorine ATOM Sodium ION Chlorine ION

The Chemistry of Life The atom is the basic unit of matter. The nucleus of an atom has protons, neutrons, and outer electrons.   Six types of atoms make up about 99% of all living organisms:  Atoms bond together to form molecules. Bonds are formed by either the sharing or the transfer of electrons. carbon hydrogen nitrogen oxygen phosphorus sulphur