Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Sep 2
Document related concepts
Hypervalent molecule wikipedia , lookup
Condensed matter physics wikipedia , lookup
Nuclear chemistry wikipedia , lookup
Electronegativity wikipedia , lookup
Inductively coupled plasma mass spectrometry wikipedia , lookup
Low-energy electron diffraction wikipedia , lookup
Isotopic labeling wikipedia , lookup
Metallic bonding wikipedia , lookup
Atomic orbital wikipedia , lookup
Stoichiometry wikipedia , lookup
Gas chromatography–mass spectrometry wikipedia , lookup
Nuclear transmutation wikipedia , lookup
Abundance of the chemical elements wikipedia , lookup
Periodic table wikipedia , lookup
Electron scattering wikipedia , lookup
Chemical element wikipedia , lookup
X-ray fluorescence wikipedia , lookup
Chemical bond wikipedia , lookup
Photosynthetic reaction centre wikipedia , lookup
Hydrogen atom wikipedia , lookup
Atomic nucleus wikipedia , lookup
Electron configuration wikipedia , lookup
Extended periodic table wikipedia , lookup
Rutherford backscattering spectrometry wikipedia , lookup
History of chemistry wikipedia , lookup
History of molecular theory wikipedia , lookup
Chemistry: A Volatile History wikipedia , lookup
IUPAC nomenclature of inorganic chemistry 2005 wikipedia , lookup
Transcript
Chapter 2: Atoms and elements A few important laws… (what is a scientific law?) Law of conservation of mass: in a chemical reaction, matter is neither Laws Law of multiple proportions: Different compounds of the same elements have whole number proportions of elements. Water and hydrogen peroxide: both have H and O Antoine Lavoisier, 1743-1794 (France) Water: 0.136 g H for every 1 g O Hydrogen peroxide: 0.0630 g H for every 1 g O Law of definite proportions: any sample of a compound will have the same proportions of elements Two different samples of CO2: Sample 1: 25.6 g O; 9.6 g C Sample 2: 21.6 g O; 8.10 g C ch2a Page 1 ch2a Page 2 Discovery of the electron Atomic theory Atomic theory: John Dalton, 1808 1. Atoms = indestructible, smallest unit of element to retain identity 2. An element has all the same type of atoms 3. A compound contains atoms of 2 or more elements in a fixed ratio J. J. Thomson, 1897: cathode ray tube 4. In a chemical reaction, atoms rearrange to form new substances Cathode rays contain a single type of particle: Negatively charged The same from any element Calculated mass/charge ratio Thomson called it the electron. ch2a Page 3 ch2a Page 4 Oil drop experiment Gold foil experiment Robert Millikan: 1909 Oil drop experiment Ernest Rutherford: 1911 gold foil experiment Charge of an electron: 1.602 x 10-19 coulombs (C) Mass of an electron: 9.109 x 10-28 g ch2a Page 5 ch2a Page 6 Nuclear model Rutherford's nuclear model: 1. Most of atom's mass is in a tiny dense nucleus 2. Most of the volume is empty space, with tiny electrons around the nucleus 3. In a neutral atom, the number of protons equals the number of ch2a Page 7
