Unit 1 Exam

Structure of water and Hydrogen bonds

Water is composed of 2 main elements, Oxygen, and Hydrogen In a 1:2 ratio

  • The bond type is covalent between the Hydrogen and Oxygen atoms because they share electrons
  • The bond between oxygen and hydrogen is polar because oxygen has a high electronegativity than Hydrogen
    • This leads to an unequal sharing of electrons and causes 2 different poles to form
    • Oxygen is the negative side and Hydrogen is the positive side

Hydrogen bonds and water properties

  • Hydrogen bonds are weak bond interactions between the negative and positive regions of two separate molecules
  • Water forms hydrogen bonds with other water molecules or with other charged molecules
  • Cohesion - When two of the same molecules form a hydrogen bond together (water collecting in drops)
  • Adhesion - when two different molecules form hydrogen bonds with each other.
  • Hydrogen bonds between water molecules lead to surface tension
    • The increased hydrogen bonding forces between water molecules at the surface
  • Water has a high solvency
    • Important because 70% of all living things are made of water, this allows cells easy access to nutrients.
    • Water makes a hydration shell around solutes
  • hydrogen bonds in ice are more ā€œorderedā€ forming a hexagonal shape with a hole in the middle, making ice less dense.
    • If ice was denser than water then aquatic life would freeze in winter
  • Waters cohesive properteies allow it to resist temputure change.
    • allows fish to stay in water on a hot day
    • Water can absorb large quantities of heat
    • Because each water molecule can make two hydregn bonds each that makes it harder to increase their motion
    • The more water vapor in the air the more heat the air can absorb
    • Large bodies of water absorb heat from warmer air and realease heat to cooler air
    • Heat is absorbed when hydrogen bonds break and realesed when the form
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  • Capillary action - adhesion and cohesion working together
    • water moving up a plants roots
  • Hydrophobic - dosenā€™t mix with water nonpolar
  • Hydrophilic- mixs with water polar
  • Colloid Fat suspended in water

Acids and Bases

  • On the Ph scale acids are below 7
  • On the PH scale acids are above 7
  • Acid is any substance that increases the H+ concdntration of a soulution
  • Base- any substance that reduces the H+ concentration of a solution
  • Buffers resist changes in concentration of H+ and OH- in a solution '
  • Ocean acidifiction is when the co2 from the atmosphere is absorbed by the ocean and taken in to creat carbonic acid
  • The PH of a solution is notated as : pH = -log [H+]
  • each Ph jump is 1*10^1

Macromolecule basics

All living things are made of these 4 classes of macromolecules

Carbohydrates

  • Includes Sugars polymers
  • Monomer: Monosaccharides
    • Glucose (C6H12O6)
    • Characterized by location of the carbonyl
    • The number of carbons in the skeletons
  • Bond: Glycosidic link
  • Polymer: disaccharide Polysacarhids
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Lipids

Proteins

Nucleic Acids

  • Macromolecules are large molecules composed of thousands of Covalently bonded atoms
  • Macromolecules are made of monomers that make polymers
  • Dehydration/condensation reaction - when two monomers are joined together through the loss of water
  • Hydrolysis - a reaction that disassembles monomers through the addition of water
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