SBI 4U1 – Unit 1

1. SBI 4U1 – Unit 1 Lesson 1 Basic Concepts in Chemistry

2. Atomic Theory • All living things are made of matter • All matter is made of atoms • Therefore all living things consist of atoms • Therefore all living things are governed by the same laws of the physical universe that govern the interactions of atoms and molecules The Laws of Thermodynamics

3. Basic Chemistry Review • 1.1 Chemical Fundaments • Bohr Diagrams allow us to determine the valence or chemically active electrons of an element • Valence number refers to the number of bonds an element is capable of forming • X = element symbol • A = # of protons = # of positive charge = # of electrons in neutral atoms • Z = atomic mass A X Z

4. Basic Chemistry Review - Ions • Elements or compounds that have acquired an electric charge • Due to the gain or loss of electrons • E.g. NaCl will dissociate in solution to form to monatomic ions: • Na+ ions have lost one electron to the chlorine ions • Cl- ions have gained one electron from sodium ions

5. Basic Chemistry Review - Ions • Many biologically active ions are polyatomic • Phosphate PO43- • Sulfate SO42- • Nitrate NO3- • Hydroxyl OH-

6. Basic Chemistry Review - Isotopes • Atoms of elements with an atomic mass that is different from the most commonly found form • E.g. 3 isotopes of carbon • C – 12; 6 protons, 6 neutrons • C – 13; 6 protons, 7 neutrons • C – 14; 6 protons, 8 neutrons • Isotopes have a variety of uses • Diagnosis – radioactive isotopes can be used to “light up” organs and tissues of interest • Treatment – used to treat a variety of soft tissue disorders including cancers • Research – radioactive isotopes can be used to track changes to biological molecules in metabolic pathways

7. Basic Chemistry Review - Bonding • Bonding allows atoms to form stable configurations as larger compounds • A sharing or distribution of valence electrons in order to stabilize outer electron orbitals • Two main types of bonds • Intramolecular – within the molecule • Ionic • Covalent • Polar Covalent • Intermolecular – between molecules • Di-pole Hydrogen bonds • Vander Waals

8. Basic Chemistry Review - Bonding Electronegativity • A measure of the tendency of a particle to attract a bonding pair of electrons • Scale ranges from 0 to 4.0 • Cesium has the lowest value 0.7 • Flourine the highest at 3.98 • ΔE values determine the type of bond • Pauling Scale is generally used to determine electronegativity values as experienced by atoms in molecules

9. Basic Chemistry Review - Bonding Ionic Bonds • ΔE>1.7 – disassociate in water • Useful for biological reactions but not for creating biological structures Covalent Bonds • ΔE = 0 – very strong and stable • Can be single, double or triple • Most common form of bonding in biological molecules Polar Covalent • 0>ΔE<1.7 • Similar to covalent but the distribution of electrons is not equal resulting in a localized electric charge