Unit 2

 

Compound

  • Two elements put together, made more stable

Ionic Bond

  • The attraction between two ions, connected by positive and negative charges.

Covalent Bond

  • Two atoms share an electron

To understand why bonds are ionic or covalent, we need to recognize that the two atoms will share electrons depending on the different in electronegativity between the two elements.

Ionic (>1.7) vs covalent (<0.4, 0.4-1.7 (polar)) is really more like two extremes on a scale

 

Electronegativity

  • The ability of an atom to draw electrons towards itself in a chemical bond

In a polar covalent bond, electrons are not shared equally. The element with the higher electronegativity pulls electrons towards itself, making one side of the molecule more positive and the other more negative. In an ionic bond, the EN difference is so great, that one element strips the electron fully away from the other.

 

 

 

Ionic

  • Tend to be between metals and nonmetals
  • One element (anion) takes electron and other element (cation) loses electron.
  • Kept together by electrostatic attraction
  • Separates into ion when in water, form strong electrolytes

Covalent

  • Tend to be between nonmetals
  • both share electrons neither forms a charged particle
  • Kept together by shared electrons, that together give each atom eight valence electrons
  • Does not generally separate in water, make poor electrolytes

Carbon-Hydrogen bonds are non-polar

Water

  • H2O
  • Superpolar

 

Surface tension

  • Small attraction of molecules that holds surface together (like water forming droplets)

Evaporation

  • Liquids get enough energy to become a gas

 

Polar molecules can dissolve ionic compounds

Polar solvents can often dissolve ionic compounds

Solubility

  • Ability to be dissolved

Solution

  • Homogenous mixture of substances

Solvent

  • Dissolving agent of solution

Solute

  • Substance that is dissolved

Aqueous Solution

  • A solution in which water is the solvent

 

CH bonds

  • Very not polar

H2O bonds

  • Very polar

The more spots to attach, the more soluble

Solubility occurs at any polar site.

Solubility in water is relative to size and polarity

 

 

 

 

Law of conservation of mass

  • Can’t make mass, can only rearrange

 

 

Every step up is 10x more than the previous step. x•10y

Disociate

  • If water (solvant) can’t dissolve acid, weak acid
  • If water (solvant) can dissolve, strong acid

 

Buffer Solution

  • Solution that resists PH change

PH

  • Acid
  1. High PH
  • Base
  1. Low PH
  • Buffer
  1. Intermediary PH

 

 

Basic stuff removes hydrogen, acidic stuff adds hydrogen

Important Unit 2

Organic Compounds

  • Carbon based molecules

Hydrocarbons

  • Compounds made of hydrogen and carbon

CHNOPS

  • Carbon
  • Hydrogen
  • Nitrogen
  • Oxygen
  • Phosphorous
  • Sulfur

 

MUST MEMORIZE

 

 

 

 

Biomolecules of life

Carbohydrates

  • Carbon and hydrogen
  • Can have other elements and atoms
  • Monosaccharides
  • Simple sugars
  • Usually have hydroxyl group (alcohol) and carbonyl group (Ketone or Aldehyde)
  • Polysaccharides
  • Starches
  • Mix well with water (hydrophilic)

Glucose

  • C6H12O6
  • Linear when ‘purified’
  • Ring-shaped when dissolved in water

Monomer

  • One molecule
  • One submolecule
  • Can be connected to others to form dimers and polymers (string)

Dimer

  • 2 connected monomers

Polymer

  • Many connected monomers
  • String
  • Chained together by covalent bonds

Glucose or Fructose

  • Glucose is hexagon
  • Fructose is pentagon

Dehydration Synthesis

  • Creates polymers
  • H and OH from monomers come together to form water
  • What is left connects through covalent bonds

Hydrolysis

  • Breaks polymers
  • H2O + enzymes break the bonds
  • Splits in two

 

Glucose + Fructose = Sucrose

 

 

Starch

  • Made by plants
  • Long string
  • Stores energy

Glycogen

  • Made by animals
  • Long strong with branches
  • Stores energy

Cellulose

  • Made by plants
  • Connected by hydrogen bonds
  • Provides structure

Lipids

  • Non-Polar
  • Don’t make strings
  • Hydrophobic

3 main types

  • Fats
  • Phospholipids
  • Steroids

Fats (triglycerides)

 

 

 

Steroids

  • Cholesterol is the primary steroid
  • All steroids come from cholesterol

 

Phospholipids

  • Main component of cell membranes

 

 

 

Proteins

  • Provide lots of functions and structural components in organisms
  • Polymers
  • Function depends on structure
  • Can be folded into different shapes
  • Different shapes provide different functions
  • Can regulate reactions
  • Can carry molecules around organism
  • Can store amino acids
  • Can carry molecules around organism

 

 

 

  • Ionic = hydrophilic
  • Hydrogen bonding = hydrophilic
  • Non-polar bonds = hydrophobic

 

 

 

  • POLYPEPTIDES ARE NOT PROTEINS
  • PROTEINS ARE ONLY FOLDED UP POLYPEPTIDES
  • Polypeptides become proteins after being folded to serve a purpose

 

 

 

 

 

 

 

 

 

 

Nucleic Acids

  • Name of the polymer
  • Two types:
  • DNA
  • RNA
  • Store, transfer, express hereditary information

Gene

  • Region of DNA that gets read and turned into RNA

 

Nucleotides will always have phosphate groups. Phosphate groups will always be the same.

  • Uracil is only found in RNA and replaces thymenes.