2.1 Life is Chemistry

Bio Flashcards

Ion

• atom/ molecule w/ net electrical charge

  • # of electrons does NOT equal # of protons (if same number, charges cancel out)

Cation

• positively charged ion

  • low electronegativity = really wants to GIVE AWAY electron (complete shell)

Anion

• negatively charged ion

  • high electronegativity = really WANTS electron (complete shell)

  • ex: chlorine → chloride

Molecule

• 2+ atoms bonded by covalent bonds

  • SHARE electrons equally

    • exist as a discrete unit + shape

Covalent Bond

• chemical bond that allows 2 atoms to SHARE electrons in their valence shell

  • strongest + most stable bond

  • hard to break + form (requires lot of energy put in)

    • good for energy storage + “permanent” structures (long-time linking)

Ionic Bond

• bond b/w 2 atoms w/ OPPOSITE charges

• transfer of electrons b/w atom that “WANTS” it more

  • turns neutral atoms → attracted ions

• “medium” strength

  • form + break easily vs cov. bonds

    • good for forming dynamic structures

      • smth nature wants to stick around but NOT permanently

• ionic compounds (salts)

Polarity

• unequal distribution of electrical charge over atoms joined by a covalent bond

  • still same # electrons + protons

    • ions are NOT POLAR b/c diff #

• net-neutral object w/ charged surface (large-scale partial charges)

Polar

• non-equal distribution of electrical charge across the 2+ atoms

Non-polar

• equal distribution of electrical charge across the 2+ atoms

Hydrogen Bond

• force b/w a partial positive charge and a partial negative charge on another molecule

  • weakest bond (strongest IMF)

  • strong when in large #’s

    • good for forming dynamic structures

    • ex: b/w 2 strands of DNA