Chapter 2 Key Terms

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  1. Physics and Chemistry
    All living organisms and their environments are subject to the basic laws of physics and chemistry
  2. Matter
    Anything that takes up space and has mass, makes up all living things
  3. Elements
    • A substance that can't be broken down into other substances by chemical reactions
    • Makes up matter
  4. Compound
    Substance consisting of 2 or more elements in a fixed ratio
  5. Essential Elements
    Carbon, hydrogen, oxygen and nitrogen make up 96% of living matter
  6. Trace Elements
    Elements required by an organism in only minute quantities
  7. Atoms
    The smallest unit of matter that still retains the properties of an element, composed of subatomic particles
  8. Neutrons
    No electrical charge
  9. Protons
    Postive charge
  10. Electrons (2)
    • Negative charge
    • Form an energy cloud around the nucleus
  11. Atomic Nucleus
    Made up of neutrons and protons
  12. Daltons
    Measurement of neutron mass and proton mass (which are identical)
  13. Atomic Number
    Number of protons in the nucleus
  14. Mass Number
    Sum of protons plus neutrons in the nucleus
  15. Atomic mass
    The atom's total mass, which can be approximated by the mass number
  16. Isotopes
    Atoms of the same element that differ in numbers of neutrons
  17. Radioactive Isotopes
    Decay spontaneously (not affected by environmental factors), giving off particles and energy
  18. Radiometric Dating
    A "parent" isotope decays into its "daughter" isotope at a fixed rate, expressed as the half life
  19. Half-life
    The time it takes an isotope to decrease by half
  20. Carbon-14
    • Used for recent biological samples
    • After death, Carbon-14 immediately starts decaying to Nitrogen-14
  21. Energy
    The capacity to cause change
  22. Potential Energy
    Associated with an object's ability to move to a lower energy state (high -> low), releasing some of the potential energy
  23. Electron Shell (2)
    • An electron's state of potential energy (furthest from nucleus = highest)
    • Electrons in different shells differ in potential energy, not position
  24. Valence Electrons (2)
    • Electrons in the outermost shell
    • Determines the chemical behavior of an atom
  25. Chemically inert
    Elements with a full valence shell
  26. Electron orbital (2)
    • 3D space where an electron is found 
    • Each electron shell consists of a specific number of orbital
  27. Covalent Bonds (2)
    • Sharing of a pair of valence electrons by two atoms
    • The shared electrons count as part of each atom's valence shell
  28. Ionic Bond (3)
    • A bond formed when electrons are stripped from one of the bonding partners
    • An attraction between an anion & a cation
    • Compounds formed= Salts
  29. Weak Bonds (2)
    • Hold many large biological molecules in their functional form
    • EX: Hydrogen bonds & Van der Waals Interactions
  30. Molecule
    Consists of two or more atoms held together by covalent bonds
  31. Single Bond
    Sharing of one pair of valence electron
  32. Double Bond
    Sharing of two pairs of valence electrons
  33. Electronegativity (2)
    • An atom's attraction for the electrons in a covalent bond
    • The more electronegative atom, the more strongly it pulls shared electrons toward itself
  34. Nonpolar Covalent Bond
    The atoms share the electron equally
  35. Polar Covalent Bond
    One atom is more electronegative, and the atoms do not share the electron equally
  36. Ion (2)
    • A charged atom
    • Transfer of an electron from Na to Cl (Ionic Bond) results in charged atoms (ions)
  37. Cation (2)
    • A "pawwwsitively" charged ion
    • It gives away on electron
  38. Anion
    a negatively charged ion
  39. Van der Waals Interactions (2)
    • Attractions between molecules that are close together as a result of these charges 
    • Individually, these interactions are weak, but collectively, these interactions can be strong
  40. Hydrogen Bond (2)
    • Forms when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom.
    • In living cells, the electronegative partners are usually oxygen or nitrogen atoms
  41. Molecular Shape
    Crucial in biology because it determines how biological molecules specifically recognize and respond to one another
Card Set:
Chapter 2 Key Terms
2017-02-13 04:22:17
biology chapter2 keyterms
key terms from chapter 2 (The Chemical Foundation of Life)
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