Atoms and elements by deepika
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Atoms and elements by deepika






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Atoms and elements by deepika Atoms and elements by deepika Presentation Transcript

  • Atoms and ElementsIsotopes and Atomic Mass 24Mg 25Mg 26Mg 12 12 12 1
  • IsotopesIsotopes Are atoms of the same element that have different mass numbers. Have the same number of protons, but different numbers of neutrons. 2
  • Nuclear SymbolA nuclear symbol Represents a particular atom of an element. Gives the mass number in the upper left corner and the atomic number in the lower left corner. Example: An atom of sodium with atomic number 11 and a mass number 23 has the following atomic symbol: mass number 23 Na atomic number 11 3
  • Nuclear SymbolsFor an atom, the nuclear symbol gives the number of Protons (p+) Neutrons (n) Electrons (e-) 16 31 65 O P Zn 8 15 30 8 p+ 15 p+ 30 p+ 8n 16 n 35 n 8 e- 15 e- 30 e- 4
  • Learning CheckNaturally occurring carbon consists of three isotopes,12C, 13C, and 14C. State the number of protons,neutrons, and electrons in each of the following. 12C 13C 14C 6 6 6protons ______ ______ ______neutrons ______ ______ ______electrons ______ ______ ______ 5
  • Solution 12C 13C 14C 6 6 6protons 6 p+ 6 p+ 6 p+neutrons 6n 7n 8nelectrons 6 e- 6 e- 6 e- 6
  • Learning CheckWrite the nuclear symbols for atoms with thefollowing subatomic particles:A. 8 p+, 8n, 8e- ___________B. 17p+, 20n, 17e- ___________C. 47p+, 60 n, 47 e- ___________ 7
  • Solution 16OA. 8p+, 8n, 8e- 8B. 17p+, 20 n, 17e- 37Cl 17C. 47p+, 60n, 47e- 107Ag 47 8
  • Learning Check1. Which of the following pairs are isotopes of the same element?2. In which of the following pairs do both atoms have 8 neutrons?A. 15X 15X 8 7B. 12X 14X 6 6C. 15X 16X 7 8 9
  • SolutionB. 12X 14X 6 6 Both nuclear symbols represent isotopes of carbon with six protons each, but one has 6 neutrons and the other has 8.C. 15X 16X 7 8 An atom of nitrogen (7) and an atom of oxygen (8) each have 8 neutrons. 10
  • Isotopes of MagnesiumIn naturally occurring magnesium,there are three isotopes. Isotopes of MgAtomic Mass 23.99 24.98 25.98% abundance 78.70 10.13 11.17Copyright © 2007 by Pearson Education, Inc. 24Mg 25Mg 26MgPublishing as Benjamin Cummings 12 12 12 11
  • Isotopes of SulfurA sample of naturallyoccurring sulfur containsseveral isotopes with thefollowing abundancesIsotope % abundance32S 95.0233S 0.75 32S, 33S, 34S, 36S34S 16 16 16 16 4.2136S 0.02 12
  • Atomic MassThe atomic mass of an element Is listed below the symbol of each Na element on the periodic table. 22.99 Gives the mass of an “average” atom of each element compared to 12C. Is not the same as the mass number. 13
  • Some Elements and Their AtomicMassMost elements have two or more isotopes thatcontribute to the atomic mass of that element.TABLE 2.9 32.07 amu 14
  • Atomic Mass for ClThe atomic mass of chlorine is Based on all naturally occurring Cl isotopes. Not a whole number. The weighted average of 35Cl and 37Cl. Copyright © 2007 by Pearson Education, Inc. 15 Publishing as Benjamin Cummings
  • Learning CheckUsing the periodic table, give the atomic mass ofeach element:A. calcium __________B. aluminum __________C. lead __________D. barium __________E. iron __________ 16
  • SolutionUsing the periodic table, give the atomic mass ofeach element:A. calcium 40.08 amuB. aluminum 26.98 amuC. lead 207.2 amuD. barium 137.3 amuE. iron 55.85 amu 17
  • The EndThanking You 18