The Chemical Context of life.

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The Chemical Context of life.
2013-10-04 16:03:48

General overview of chemistry
Show Answers:

  1. What is matter?
    Matter is anything that takes up space and has mass.
  2. Define element.
    An element is a substance that cannot be broken down to other substances by chemical reaction.
  3. Define compound and give an example.
    A compound is a substance consisting of two or more elements in a fixed ratio. Water is an example.
  4. What are the 6 elements of life?
    Carbon, oxygen, hydrogen, nitrogen, sulphur and phosphorus
  5. What is an atom?
    An atom is the smallest unit of matter that still retains the properties of an element.
  6. What are atoms composed of?
    Atoms are composed o subatomic particles that include electron (-1), proton (+1) and neutron (0)
  7. Where are the subatomic particles found?
    • Electron- revolving around the nucleus
    • Proton and neutron- inside nucleus
  8. What is an elements atomic number?
    It's the number of protons in its nucleus
  9. What is an elements mass number?
    It's the sum of protons plus neutrons in the nucleus
  10. What are isotopes?
    Isotopes are two atoms of an element that differ in number of neutrons.
  11. What is potential energy?
    It's the energy that matter has because of its location or structure.
  12. An electron's state of potential energy is called its energy level or ___________.
    electron shell
  13. The further the electron is from the nucleus.....
    The higher the potential energy because it's more unstable when it's further from the nucleus.
  14. The closer the electron is to the nucleus...
    The lower the potential energy because it's more stable near the nucleus.
  15. The chemical behaviour of atoms is determined by the ______________ in __________.
    Distribution of electrons in electron shells.
  16. What are Valence electrons?
    Electrons in the outermost shell or valence shells.
  17. Elements with a full valence shell are chemically __________.
  18. Atoms in which the outermost shell is not completely filled with electrons tend to be _________.
    Chemically reactive.
  19. What is an orbital?
    It's the three-dimensional space where an electron is found 90% of the time.
  20. No more than how many electrons can occupy the same orbital?
  21. What are the orders of orbitals in the first 3 valence shells?
  22. Atoms with incomplete valence shells can share and transfer ___________ with certain other atoms.
    Valence electrons.
  23. What is a covalent bond?
    It's the sharing of a pair of valence electrons by two atoms.
  24. How are molecules held together?
    A molecule consists of two or more atoms held together by covalent bonds.
  25. What is a compound?
    It's a combination of two or more different elements.
  26. What is electronegativity?
    It's an atom's attraction for the electrons in a covalent bond.
  27. What two elements have similar electronegativity?
    Carbon and Hydrogen
  28. What two elements are more electronegative than carbon and hydrogen?
    Oxygen and nitrogen
  29. what is a nonpolar covalent bond?
    In a nonpolar covalent bond, the atoms share the electrons equally.
  30. What is a polar covalent bond?
    In a polar covalent bond, one atom is more electronegative, and the atoms do not share the atoms equally.
  31. What does unequal sharing of electrons cause?
    It causes a partial positive or partial negative charge for each atom or molecule.
  32. Is water nonpolar or polar?
    Water is a polar molecule.
  33. What is an ionic bond?
    When atoms sometimes strip electrons from their bonding partners (transfer electrons).
  34. What is a charged atom (or molecule) called?
    It's called an ion.
  35. What is a cation?
    Positively charged ion.
  36. What is an anion?
    Negatively charged ion.
  37. What is an ionic bond?
    It's an attraction between an anion and a cation.
  38. What are compounds formed my ionic bonds?
  39. Which bonds are the strongest and weakest?
    Covalent bonds are stronger. Ionic and hydrogen bonds are weaker.
  40. Why are weak chemical bonds important?
    They reinforce shapes of large molecules and help molecules adhere to each other.
  41. What is a hydrogen bond?
    It forms when a hydrogen atom is covalently bonded to one electronegative atom, which is also attracted to another electronegative atom. usually attracted to oxygen and nitrogen.
  42. What are Van der Waals Interactions?
    They are attractions between molecules that are close together as a result of these charges. They have transient interactions.
  43. What are chemical reactions?
    It involves the making and breaking of chemical bonds. They are all reversible.
  44. What are the starting and final molecules in the chemical reaction called?
    • starting molecule: reactants
    • final molecule: products
  45. What Is chemical equilibrium?
    Chemical equilibrium is reached when the forward and reverse reactions rates are equal.