BASIC CHEMISTRY FOR UNDERSTANDING BIOLOGY

Basic Terms Atom – the smallest component of matter Proton (+) Neutron (neutral) Electron (-)

Elements 96% of all living things made of 4 elements: Element – pure substance composed of one type of atom 96% of all living things made of 4 elements: Oxygen (65%) Carbon (18.5%) Hydrogen (9.5%) Nitrogen (3%).

Reading the Periodic Table

Remember this!!!! Atomic number = # of protons Atomic mass= #protons + # neutrons Neutrons= atomic mass - # protons The ATOMIC # determines what element the atom is. This stays constant.

Analyzing an element Element? Atomic Mass? Atomic Number? How many? Protons Neutrons Electrons

Electron configuration Shells, orbitals, energy levels 1st : 2 e- 2nd : 8e- 3rd : 18e- *(temporarily stable w/ 8) 4th : 32e-

Electron Configuration

Terms to know Isotopes, ions, new elements

Isotope Same number of protons in atom, but different # of neutrons

Reactivity A partly-filled energy level makes some atoms chemically reactive—wants to fill their highest energy levels.

Bonds

Ionic bonds - formed by the attraction between two oppositely charged ions. (Ex: NaCl) *electrons are completely transferred from one atom to another

Ionic Bonds

Covalent Bonds sharing of electron pairs between atoms, strong (Ex: CH4)

Hydrogen Bonds Attractive interaction of a hydrogen atom with an electronegative atom, fairly weak

Water ¾ earth covered in H20 66% of human body (+) (-) *Polar molecule: Doesn’t share the electrons evenly (+)

Hydrogen bonds (weak) H2O molecules are attracted to each other Gives water its unique characteristics

SOLUTE is what’s being dissolved in SOLVENT. This forms a SOLUTION. Best SOLVENT on Earth…..meaning it will dissolve more compounds than any other liquid SOLUTE is what’s being dissolved in SOLVENT. This forms a SOLUTION. SOLUTE SOLVENT

Water as a solvent Dissolves ionic compounds especially well Water molecules surround and separate positive and negative ions

Boil H2O  molecules motion  break bonds Freeze H2O  molecules motion  spaced apart in fixed crystal formation Solid ICE EXPANDS and is LESS dense than water! Weird.

Cohesion When water molecules are attracted to each other (attraction between like-substances) “Dome shape” of a drop. Molecules on surface are holding each other tight, creating surface tension

Helps insects walk across water Cohesion … Helps insects walk across water

Adhesion Attraction between UN-LIKE substances (water to side of tube) Capillary action-water molecules will “climb”, pulling each other up a thin tube Capillary action; combo of cohesion/adhesion 1

Transpiration is like capillary action in plants Transpiration is like capillary action in plants. process which plants/trees remove water from the soil

High heat capacity Water can absorb a lot of heat energy before it raises temperature When does Lake Michigan temp become tolerable? Thank you!

Properties of Water : pH Water itself is partly ionized H2O    H+ + OH- pH Scale 1-14 Acidic pH = 1-6 More H+ ions Neutral pH = 7 Basic pH = 8-14 Bases accept H+ ions, lots of OH-