bio 109- CHAPTER 2- redox reaction and forces of attraction

element

a substance which cannot be brok en down into other substances

compound

contains 2 or more elements, held together by inTRAmolecular forces

molecule

2 or more atoms held together in a stable association, held together by inTRAmolecular forces

ionic

atom/molecule with a full electrical charge

compounds that involve a metal binding with either a non-metal or a semi-metal opposite charges attract

redox reaction creates ions

not actually bonded just strongly attracted

polar

asymetrical- unequal sharing of electrons

electronegativity difference >0.5

create dioples

strong inTRAmolecular forces

non-polar

symetric- equal sharing of electrons

electronegativity difference < 0.5

electronegativity

atoms ability to attract electrons

ranges from 4.0 (f) - 0.7 (Cs)

differences affect electron distribution within a covalent bond

covalent bond

chemical bond formed when two electrons are shared between two atoms

more electrons shared= greater strength of the bond

what kind of bond is this

covalent bond

what kind of bond is this

ionic bond

what kind of bond is this

polar

what kind ofbond is this

non polar

inTRAmolecular forces

hold adjacent atoms together WITHIN a molecule

inTERmolecular forces

attract DIFFERENT MOLECULES (or parts of molecules) together

what are atoms composed of?

protons

neutrons

electrons

protons

positive charge, located in the nucleus

neutrons

no charge, located in the nucleus

electrons

negative charge, found in orbitals surrounding the nucleus, have potential energy related to their position- farther away from nucleus=more energy

OIL

RIG

oxidation is loss of an electron (and energy)

reduction is gain of an electron (and energy)

weak electronegativity

carbon- 2.5

sulfur- 2.5

hydrogen- 2.1

phosphorus- 2.1

strong electronegativity

oxygen- 3.5

nitrogen- 3.0

chlorine- 3.0

dipole - dipole interactions

attractions of opposite partial charges

depends on polar inTRAmolecular forces

ex- polar cov bond

weaker inTERmolecular forces

London dispersion forces (LDF)

general attraction between any 2 molecules

more electrons in atom= stronger forces

WEAKEST force of attraction

catalyst

substance that speeds up a chemical reaction, or lowers the temperature or pressure needed to start one, without itself being consumed during the reaction

buffers

substances that resist changes in pH

releasing H+ when a base is added

absorbing H+ when acid is added

overall effect= keeps [H+] relatively constant

bases

combines with H+ in water to decrease [H+] (increase pH)

pH greater than 7

conduct electricity

slippery to touch

acids

dissociates in water= increase [H+] (lower the pH)

pH less than 7

acids are electrolytes

react with active metals to yield hydrogen gas

are strong ionic compounds water souluble

they are less water soluble, harder to dissociate ions

does dissolving glucose create ions

no

cohesion

dipole-dipole (hydrogen bond) inTERmolecular forces

creates surface tension

adhesion

water molecules attracted to other polar molecules

dipole dipole (hydrogen bond) inTERmolecular forces

properties of water

high specific heat- lots of energy to change temp, many dipole- dipole forces

high heat of vaporization- lots of energy for phase change, many dipole-dipole forces

water is more dense than ice- fixed dipole- dipole, more empty space, ice floats in water

can form ions

are nonpolar molecules soluble

no they are insoluble, cannot form dipole- dipole attractions

hydrophobic

are polar molecules and ions soluble?

yes they are soluble, form dipole- dipole, or ion- dipole

hydrophilic