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PS_102_STUDY_GUIDE_(CH._14-19)[1]

# PS_102_STUDY_GUIDE_(CH._14-19)[1] - TUDY GUIDE(CH 14-19...

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TUDY GUIDE (CH. 14-19) ATOMS & PERIODIC TABLE The elements (natural & synthetic)-88 “natural” elements, others are “synthetic” Human Body is made of-Oxygen, Carbon, Hydrogen (largest percentage) approx. 70% of body is water Symbols (Latin, Greek, etc. & English)-Berzelius, responsible for original symbols, many symbols come from Latin, Greek names for element-thus unusual symbols! Ex. Na- sodium Pb-lead Au-gold Sn-tin Elements come in different forms, same elements-structured differently: Allotropes Size of Atoms-distance f/m nucleus to first electron is about 5,000X the size of the nucleus. Mostly space Ex. IF the nucleus were .3 inches in diameter, the first electron would be 164 feet away! The nucleus (Rutherford) Protons (Rutherford) Neutrons (Chadwick) Orbiting electrons (Thompson) Atomic number (protons in nucleus; gives identity)-Gives the “identity of the element. It tells us the number of Protons (+) in the nucleus of ANY atom of that element. This number is essential to predicting the various physical and chemical properties of that element. Mass number (protons + neutrons in nucleus)-Gives the “total” of the number of protons AND NEUTRONS (o) in the nucleus of that particular atom. Remember the mass number also tells which isotope of that element is represented. Since each proton AND each neutron contribute one AMU (atomic mass unit) 1/12 of a carbon 12 mass is an AMU>to the atom’s mass, the mass number is the total of these. Isotopes (#protons same; different #neutrons) H1-normal hydrogen sometimes call (protium) 1 proton no neutrons H2-deuterium 1 proton and 1 neutron H3-tritium has 1 proton and 2 neutrons Isotopes-act the same why chemically but differently nuclerly Every element has at least one isotope. Atomic mass (average mass of isotopes in typical sample)-Average of marses of isotopes in a typical sample of the element. Based on amu units with “carbon-12” as the standard. Atomic mass unit (AMU; based on carbon-12 atom) At. Mass unit Electron -1 charge 1/1838 of an AMU Proton +charge 1 of an AMU Neutron 0charge 1 of an AMU In chemical reactions and calculations, electrons are considered to have “negligible mass” Periodic Table (Mendeleev, Russian) Atoms do not have charges

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In chemical reactions and calculations, electrons are considered to have eligible mass Periodic Table (Mendeleev, Russian) Halogens (group 7) salt maker Most elements found as solids at normal temperatures. Only mercury and bromine found in liquid form at room temperature and normal pressure. First periodic table of elements in 1869-Mendeleev.
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