Wednesday, September 14, 2016

Ch. 2 | introductory chemistry

chemistry: science of structure & interactions of matter & energy
matter: anything that occupies space & has mass
  • solid: definite shape, definite volume
  • liquid: no definite shape, definite volume
  • gas: no definite shape, no definite volume
energy: ability to do work
  • kinetic energy: energy of motion
  • potential energy: stored energy 
4 big elements (that make up 96% of all living matter): 
  1. hydrogen
  2. oxygen
  3. nitrogen
  4. carbon
atoms: building blocks of elements 

basic particles:
  1. protons: positively charged 
  2. electrons: negatively charged 
  3. neutrons: uncharged
atomic number: number of protons in an atom
mass number: number of protons + neutrons in an atom

isotopes: atoms of the same element w same amount of protons & electrons, but different number of neutrons

ion: an atom that gives up or gains electrons to conform to the octet rule (get 8 valence electrons)
ionic bond: electrical attraction (btwn positively & negatively charged ions) holding ions together
covalent bond: shared electron pair btwn 2 atoms 

polar molecules: one atom attracts electrons more strongly than the other --> one end of molecule has partial negative charge & other end has partial positive charge
non-polar molecules: share valence electrons equally btwn atoms 

chemical reaction: occurs when new bonds form/old bonds break; involves transfers of energy 
  • synthesis: atoms/ions/molecules combine to form new/larger molecules (anabolic)
  • decomposition: molecule is split apart (catabolic)
solute: substance/material that has been dissolved in a solvent
solvent: liquid/gas in which other material/solute has been dissolved

water: most important/abundant inorganic compound
  1. water is the universal solvent- polar substances dissolve easily in water 
  2. water participates in chemical reactions- hydrolysis (addition of water to break down molecules) & dehydration synthesis (water molecule is removed from reactants)
  3. water absorbs & releases heat very slowly- helps maintain body temperature
  4. water requires a large amount of heat to change from liquid to gas- good cooling mechanism
  5. water serves as a lubricant- saliva, mucus, etc. 
carbohydrates: major energy sources for the body
  1. monosaccharides: simple sugars 
  2. disaccharides: double sugars- sucrose 
  3. polysaccharides: complex carbs- glycogen (broken down when glucose is needed); starches (found in plants)
lipids: store energy & comprise cell membranes & hormones 
  1. triglycerides
  2. fatty acids 
  3. phospholipids (make up lipid bilayer)
  4. steroids 
  5. fat-soluble vitamins (A, D, E, K)
  • fibrous: structural proteins
  • globular: mobile, many functions
  • antibodies: defend body against invading microbes
  • hormones: protein messengers
  • enzymes: speed up chemical reactions 
                3 properties of enzymes:
    1. specificity: certain chemical w certain reactant (lock & key)
    2. efficiency: catalyze reactions at high rates
    3. control: controlled by many factors like genes, binding substances, cofactors, etc.
    amino acids: building blocks of proteins
    • peptide bond: amino acid covalent bond
    • dipeptide: 2 amino acids linked together
    • tripeptide: 3 amino acids linked together
    • polypeptide: 4+ amino acids linked together 
    nucleic acids: carry genetic instructions 
    nucleotides: building blocks of nucleic acid molecules 
    3 parts of nucleotides:
    1. nitrogenous bases (adenine, guanine, thymine, cytosine)
    2. 5-carbon monosaccharide (DNA or RNA)
    3. phosphate group 
    deoxyribonucleic acid (DNA): forms genetic material 
    ribonucleic acid (RNA): relays instructions from genes

    adenosine triphosphate (ATP): chemical that stores & releases energy for chemical reactions in cells

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