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Nomenclature Review and the MOLE

Nomenclature Review and the MOLE. September 19 2011. Reviewing the atom. ATOM – smallest piece of an element. Nucleus Very dense, almost all the mass of the atom, but very small Protons – positively charged, one AMU Neutrons – no charge (neutral), one AMU Energy levels

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Nomenclature Review and the MOLE

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  1. Nomenclature Review and the MOLE September 19 2011

  2. Reviewing the atom • ATOM – smallest piece of an element

  3. Nucleus • Very dense, almost all the mass of the atom, but very small • Protons – positively charged, one AMU • Neutrons – no charge (neutral), one AMU • Energy levels • Electrons – e- -negatively charged, very small • First energy level – only two electrons • Later energy levels – eight electrons

  4. Name that atom…

  5. Atoms and Ions • ATOMS – smallest piece of an element • GROUND STATE – overall zero charge • Equal numbers of protons and electrons • IONS – atoms with charges! • Electrons have been stolen… the imbalance of protons (positive) and electrons (negative) results in a charged particle

  6. Atoms and Ions • Chlorine has 17 protons and 17 electrons • The chloride ion stole an electron from another atom… it now has 17 protons and 18 electrons • It has a negative charge because it has more electrons than protons

  7. Name that atom or ion…

  8. Predicting the charges of ions • How can we determine what charge an ion will have? • The OCTET rule… atoms want to be like noble gases and have eight electrons in their valence (outer) energy level • We can predict charges with groups of the periodic table

  9. Predicting charges… oxidation numbers 0 1+ 1- 2- 2+ 3+ 3-

  10. Polyatomic ions • Groups of atoms that share electrons with each other, but then steal more! • Or electrons they were sharing were stolen from them… • Names do NOT end in -ide 1+

  11. Ions and Ionic Compounds • Ions with opposite charges are attracted to each other like magnets • We call this attraction an ionic bond • Compounds formed by ionic bonds are called ionic compounds • Charges are shown with little numbers up = superscript… K1+ • Numbers of ions in the formula are shown with little numbers down = subscript… O2

  12. How do we name IONIC compounds? • We balance the charges of the ions • Potassium fluoride • K1+ + F1- -> KF • Lithium oxide • Li1+ + O2- -> Li2O • Magnesium bromide • Mg2+ + Br1- -> MgBr2

  13. Ionic and Molecular Compounds

  14. Naming acids • Naming acids is similar to naming ionic compounds… • Cl- is chloride • HCl is hydrochloric acid • SO42- is sulfate • H2SO4 is sulfuric acid

  15. Counting particles… the MOLE • Not this mole…

  16. The MOLE • This mole… 6.02 x 1023

  17. Avogadro • Amedeo Avogadro, 1811 - proposed that the volume of a gas at a given pressure and temperature is proportional to the number of molecules or atoms of the gas, no matter how large or small each atom or molecule is • In other words, more molecules = more volume

  18. Avogadro’s constant • Many scientists… Jean Perrin, JJ Loschmidt, Robert Millikan, Michael Faraday… over many years were involved in experiments that led to the determination of the number of molecules • In 1906, Jean Perrin proposed naming the number in honor of Avogadro… • Avogadro’s number = 6.02 x 1023

  19. The mole and molecular mass • One mole of a substance has a gram mass equal to the atomic mass (AMU)of that substance • Carbon-12 has a mass of 12 AMU • One mole of Carbon-12 has a mass of 12 g • One molecule of H2O has a mass of 18 AMU • One mole of H2O has a mass of 18 g • So if you have 18 g water, you have… 6.02 x 1023 molecules of water

  20. Practice…

  21. Dimensional Analysis • Switching between units • Atomic mass <-> molar mass <-> moles • Kilometers <-> Meters <-> Centimeters Unit conversion factors 100 m = __?__ cm 100 m x 100 cm = 10,000 cm 1 m

  22. Practice… • 1 hour = ______ seconds 1 hr x 60 min x 60 sec = 3600 seconds 1 hr 1 min • 1 year = ______ seconds 1 yr x 365 days x 24 hr x 60 min x 60 sec = 31,536,000 seconds 1 yr 1 day 1 hr 1 min • 60 miles/hr = ________ feet/second 60 mi x 5280 ft x 1 hr x 1 min = 88 feet/sec 1 hr 1 mi 60 min 60 sec

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