Chem 121 terms

Card Set Information

Chem 121 terms
2012-10-29 19:51:19

Chem terms
Show Answers:

  1. What is chemistry?
    The study of matter.
  2. Rules for sig figs (5)
    • 1. Nonzero are always sig figs
    • 2. Zeroes at beginning are never sig
    • 3. Zeroes between non zero are always
    • 4. Zeroes at the end of a number with decimal are always sig
    • 5. Zeroes at the end of a number with no decimal points may or may not be sig depending on exactness of the number.
  3. Mass
    Quantity of matter in an object.
  4. What are the three states of matter?
    Solid,liquid and gas
  5. What s density?
    Mass per unit volume
  6. Specific gravity
    Comparison of density with that of water.
  7. Energy
    Capacity to do work
  8. Kinetic energy
    Energy of motion-any moving object
  9. Potential energy
    Stored energy-drawn bow, water held bavk by dam
  10. Specific heat
    Amount of heat necessary to raise 1 gram of a substance by 1°C
  11. Heat
    A form of energy, measured in calories
  12. Factor-label method
    Units are multiplied and divided while crossing out unit labels. For conversions.
  13. Scientific method
    Testing of hypotheses and theories by collecting facts.
  14. Chemical change
    Substances are used up and others formed.
  15. Physical change
    Substances do not change their identity.
  16. Pure substances
    Fixed composition, cannot be further purified
  17. Mixtures
    Combination of two or more pure substances
  18. Pure substances can be (2):
    • Elements-cannot be subdivided by physical or chemical means
    • Compounds-elements united in fixed ratios
  19. Mixtures can be (2):
    • Homogeneous matter-uniform composition throughout
    • Heterogeneous matter-nonuniform composition
  20. Atom
    The smallest particle that retains the chemical properties of the element. The interaction among atoms accounts for the properties of matter.
  21. Dalton's atomic theory (5)
    • All matter is made up of tiny, indivisible particles called atoms
    • All atoms of a given element have the same chemical properties.
    • In ordinary chemical reactions, no atom of any element disappears or is changed into another element.
    • Compounds are formed by the chemical combination of two or more different kinds of atoms. In a given compound, the relstive numbers of each type of atom are constant and most commonly expressed as integers.
    • A molecule is a tightly bound combination of two or more atoms that act as a single unit.
  22. Antoine lavoisier
    • Evidence for dalton's theory-
    • Antoine lavoisier discovered the law of conservation of mass-no matter can be eier created or destroyed.
  23. Joseph Proust
    Law of constant composition-any compound is always made up of elements in the same proportion by mass.
  24. Monotomic, diatomic and polyatomic elements
    How many atoms cling together-helium and neon are monatomic, oxygen contains two atoms in each molecule.
  25. Diatomic molecules (7):
    • Free atoms do not exist
    • O2 oxygen
    • H2 hydrogen
    • N2 nitrogen
    • F2 fluorine
    • Cl2 chlorine
    • Br2 bromine
    • I2 iodine
  26. Polyatomic elements
    • O3 ozone
    • P4 phosphorus (one form)
    • S8 sulfur ( one form)
    • Diamond-millions of carbon atoms
  27. Atomic number
    Z-number of protons in the nucleus
  28. AMU
    • Atomic mass unit-relative scale of masses of atoms
    • 1 amu is 1/12 the mass of a carbon atom containing 6 protons and 6 neutrons
  29. Particles and charges
    • Proton +1
    • Electron -1
    • Neutron neutral
  30. Amu
  31. Mass number
    Sum of the number of protons and neutrons in its nucleus. Electrons are so small they dont count
  32. Isotopes
    Determined by different number of neutrons. Has different mass number.
  33. Atomic weight
    Weighted average of the masses in amu of its isotopes found on earth. The weight is very close to its mass number because protons and neutrons have an approx mass of 1 amu
  34. Dmitri Mendeleyev
    Invented periodic table. Started by arranging elements in order of increasing atomic weight. He noted that certain properties occur periodically.