Basic Chemistry

1. Basic Chemistry

2. Chemical Elements • Matter – anything that takes up space and has mass • Composed of elements • Element – substance that cannot be broken down to simpler substances with different properties • All living and nonliving things are matter composed of elements

3. The Atom – John Dalton • Smallest part of an element that displays the properties of the element • Subatomic particles • Neutron – neutral charge • Proton –positive charge • Electron – neg. charge

4. The atom • Atomic number = # of protons (usually # of electrons if atom is neutral) • Atomic mass = protons and neutrons • # of neutrons = Atomic mass – P+

5. Periodic Table Dimitri Mendeleev

6. Periodic table • Vertical columns – groups • Group 8 – noble gases, do not react • Horizontal rows – periods

7. Isotopes • Isotope – atoms of same element that differ in # of neutrons • Carbon 14 is a radioactive isotope • Used for medical procedures – tracers • Radiation can be used to sterilize and beneficial

8. Bohr Model – Niels Bohr • orbital (volume of space) • Energy levels • electron shells of 2, 8, 8 • Ex. Sulfur – 16 • 3rd period (3 shells), • 6th group, 6 electrons in outer shell • Octet rule – stable if outer shell is full

9. Elements and compounds • Compound – atoms of 2 or more different elements bond together • Molecule – smallest part of a compound that still has the properties of that compound

10. Bonding • Ions – electrically charged particles • Ionic bond – gives or receives an electron • NaCl • Covalent bonds – 2 atoms share electrons • Double covalent bond – 2 atoms share 2 electrons ex. Oxygen gas

11. bonding • Nonpolar covalent bond - sharing of electrons between 2 atoms is fairly equal • Polar covalent bond – unequal sharing of electrons ex. Water • Hydrogen bonding – caused by polarity of hydrogen and oxygen in water molecule, DNA

12. Chemistry of water • All living things 70 – 90% water • Water molecules cling together with hydrogen bonding • Properties: • High heat capacity • High heat of vaporization • A solvent • Cohesive and adhesive • High surface tension • Frozen water is less dense than liquid water

13. High heat capacity • slow to heat or cool • Calorie – amt of energy to convert 1 g of water 1 C • Why important??

14. High heat of vaporization • liquid to gas • Hydrogen bonds must be broken • Allows for efficient way to release excess body heat

15. Water is solvent • Solution – contains dissolved substances • Solute – the substance dissolved • Dissociation of water • Na+ attracted to oxygen -, Cl- attracted to hydrogen+ • Hydrophillic – attracted to water • Hydrophobic repel water (nonpolar)

16. Cohesive and adhesive • Cohesion – attracted to each other • Adhesion – attracted to other surfaces • Capillary action • High Surface tension – strong force between water molecules • Water striders

17. Frozen water is less dense than liquid water • Water cools, molecules move together • Hydrogen bonding is more rigid and more open • Less dense – floats • What would happen if ice did not float?

18. Acids and bases • Hydrogen ions (H+) • Hydroxide ions (OH-) • Acids – High H+ concentration when dissociation in water • Lemon juice, vinegar, tomatoes • Basic – low H+ concentration, release hydroxide ions • Ammonia, rel

19. pH scale • Indicates acidity and alkalinity of a solution • 0 – 14, 7 is neutral H+ = OH- • Below 7 = acid • Above 7 = basic • Each unit has 10 times the H+ of the previous unit as you move down

20. Buffers • Chemical s that keeps pH within normal limits • Resist pH changes because they can take up excess H+ or OH- • Blood = 7.4 • If drops = acidosis, rises = alkalosis • Carbonic acid/ bicabonate ions in body to regulate pH