Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
CHEMISTRY of the Atom QuickTime™ and a Cinepak decompressor are needed to see this picture. CHEMISTRY of the Atom 1 PARTICLES: Mass Charge Symbol Nucleus: PROTON 1 amu +1 H+, H, p NEUTRON 1 amu 0 n _________________________________________ ELECTRON very small -1 eThe particle is said to “hold” atoms together in molecules. © Copyright 1998-2000 R.J. Rusay Periodic Table 1 • Mendeleev’s Table 1868-1871 Mural at St.Petersburg University, Russia © Copyright 1998-2000 R.J. Rusay Periodic Table Elements are classified by: properties & atomic number metals, non-metals, metalloids Groups or Families (vertical) 1A = alkali metals 2A = alkaline earth metals 7A = halogens 8A = noble gases Periods (horizontal) Group 1 and Group 2 Metals QuickTime™ and a Cinepak decompressor are needed to see this picture. Modern Periodic Table 1 From Los Alamos National laboratory: © Copyright 1998 R.J. Rusay Using the Periodic Table QuickTime™ and a Cinepak decompressor are needed to see this picture. Atoms, Molecules & Ions 1 Atoms: • # Protons = Atomic Number • Atomic Mass = # Protons + # of Neutrons • Isotope: same atomic number but different atomic mass • Periodic Table atomic mass is a weighted average of isotopic masses © Copyright 1998-2000 R.J. Rusay Atoms, Molecules & Ions 1 Atomic Mass of Carbon: Exact Mass 12.00000 98.98 13.00335 1.110 14.00 % Occurence negligible What is the “weighted” atomic mass? © Copyright 1998-2000 R.J. Rusay Atoms, Molecules and Ions 1 • • • • • Atomic Number = 6 (atom’s identity) Carbon Atomic Mass = 13 (isotope 13) 6 protons; # neutrons = 13 - 6 neutral atom has 6 electrons © Copyright 1998-2000 R.J. Rusay Atomic Symbols Mass number 39 K 19 Element Symbol Atomic number Atoms, Molecules and Ions 1 • • • • • Atomic Number = 12 (atom’s identity) Atomic Mass = 24 12 protons; # neutrons = 24 - 12 neutral atom has 12 electrons Ion contains 10 electrons: symbol? 24 12 +2 Mg • 12 p+ + 10e- = +2 © Copyright 1998-2000 R.J. Rusay Atoms, Molecules and Ions 1 • • • • • Atomic Number = 17 (atom’s identity) Atomic Mass = ? # protons = ? ; # neutrons = ? neutral atom has ? electrons Ion contains 18 electrons: symbol? 35 17 -1 Cl • 17 p+ + 18e- = -1 © Copyright 1998-2000 R.J. Rusay Ions Cation: A positive ion Mg2+, NH4+ Anion: A negative ion Cl, SO42 Ionic Bonding: Force of attraction between oppositely charged ions. Molecules Neutrally Charged Eg. Salt: NaCl -> 1 Na+ and 1 Cl What is the proportion of ions for a compound formed from Mg ion and chlorine? Mg2+ and Cl 1 Mg2+ combines with 2 Cl Chemical Formulas Molecular Formula: Elements’ Symbols = atoms Subscripts = relative numbers of atoms How many atoms of each element are in the following componds? MgCl2 CCl4 NaOH (NH4) 2CO3 C20H26N2O (Ibogaine, not ionic)