lectureplus timberlake1 atoms and elements the atom atomic number and mass number isotopes

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  • LecturePLUS Timberlake*Atoms and ElementsThe AtomAtomic Number and Mass NumberIsotopes

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*

    LecturePLUS Timberlake

  • The Atom

    An atom is the smallest particle that retains the characteristics of an element

  • LecturePLUS Timberlake*Atomic TheoryAtoms are building blocks of elements Similar atoms in each elementDifferent from atoms of other elementsTwo or more different atoms bond in simple ratios to form compounds

    LecturePLUS Timberlake

  • The Parts of the AtomAtoms are composed of three subatomic particles:

    Protons have a positive charge (+)

    Electrons carry a negative charge (-)

    Neutrons are electrically neutral.

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Subatomic ParticlesParticleSymbol Charge RelativeMass Electron e-1- 0

    Proton p++ 1

    Neutron n0 1

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Location of Subatomic Particles 10-13 cm electrons

    protons neutrons

    10-8 cmnucleus

    LecturePLUS Timberlake

  • The Structure of the Atom The protons and neutrons, each with a mass of about 1 amu are found in the tiny, dense nucleus.

    The electrons are located outside the nucleus.

    LecturePLUS Timberlake

  • Models of the Atom*

  • LecturePLUS Timberlake*Atomic Number Counts the number of protonsin an atom

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Atomic Number on the Periodic Table11NaAtomic NumberSymbol

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*All atoms of an element have the same number of protons11Na11 protonsSodium

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Periodic TableRepresents physical and chemical behavior of elementsArranges elements by increasing atomic numberRepeats similar properties in columns known as chemical families or groups

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Periodic Table 1 2 3 4 5 6 7 8

    11 Na

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Learning Check State the number of protons for atoms of each of the following:A. Nitrogen 1) 5 protons 2) 7 protons 3) 14 protonsB. Sulfur 1) 32 protons 2) 16 protons 3) 6 protonsC. Barium1) 137 protons 2) 81 protons 3) 56 protons

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Solution State the number of protons for atoms of each of the following:A. Nitrogen 2) 7 protons B. Sulfur 2) 16 protonsC. Barium3) 56 protons

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Number of ElectronsAn atom is neutral The net charge is zeroNumber of protons = Number of electronsAtomic number = Number of electrons

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Mass Number

    Counts the number of protons and neutronsin an atom

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Atomic SymbolsShow the mass number and atomic numberGive the symbol of the elementmass number 23 Na sodium-23 atomic number11

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Subatomic Particles in Some Atoms163165 O P Zn 815308 p+15 p+30 p+8 n16 n35 n8 e-15 e-30 e-

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*IsotopesAtoms with the same number of protons, but different numbers of neutrons. Atoms of the same element (same atomic number) with different mass numbers Isotopes of chlorine35Cl37Cl1717 chlorine - 35 chlorine - 37

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Learning Check Naturally occurring carbon consists of three isotopes, 12C, 13C, and 14C. State the number of protons, neutrons, and electrons in each of these carbon atoms. 12C 13C14C 6 6 6#p _______ _______ _______ #n _______ _______ _______ #e _______ _______ _______

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Solution12C 13C 14C 6 6 6#p 6 6 6 #n 6 7 8#e 6 6 6

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Learning Check An atom of zinc has a mass number of 65. A.Number of protons in the zinc atom 1) 302) 353) 65

    B.Number of neutrons in the zinc atom 1) 302) 353) 65

    C. What is the mass number of a zinc isotope with 37 neutrons? 1) 372) 653) 67

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Solution An atom of zinc has a mass number of 65. A.Number of protons in the zinc atom 1) 30 B.Number of neutrons in the zinc atom2) 35

    C. What is the mass number of a zinc isotope with 37 neutrons?3) 67

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Learning Check Write the atomic symbols for atoms with the following:

    A. 8 p+, 8 n, 8 e-___________

    B.17p+, 20n, 17e-___________C. 47p+, 60 n, 47 e- ___________

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Solution 16OA. 8 p+, 8 n, 8 e- 8

    B.17p+, 20n, 17e- 37Cl 17 C. 47p+, 60 n, 47 e-107Ag 47

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Learning Check AT 5An atom has 14 protons and 20 neutrons.A.Its atomic number is1) 142) 163) 34

    B. Its mass number is1) 142) 163) 34

    C. The element is1) Si2) Ca 3) Se

    D.Another isotope of this element is1) 34X 2) 34X 3) 36X 16 14 14

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Solution AT 5An atom has 14 protons and 20 neutrons.A.It has atomic number1) 14

    B. It has a mass number of3) 34

    C. The element is1) SiD.Another isotope of this element would be3) 36X 14

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Masses of AtomsA scale designed for atoms gives their small atomic masses in atomic mass units (amu)An atom of 12C was assigned an exact mass of 12.00 amuRelative masses of all other atoms was determined by comparing each to the mass of 12C An atom twice as heavy has a mass of 24.00 amu. An atom half as heavy is 6.00 amu.

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Atomic Mass on the Periodic Table11Na22.99Atomic NumberSymbolAtomic Mass

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Atomic MassListed on the periodic tableGives the mass of average atom of each element compared to 12C Average atom based on all the isotopes and their abundance %Atomic mass is not a whole number

    Na22.99

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Atomic MassAtomic mass is the weighted average mass of all the atomic masses of all the isotopes of that atom.

    LecturePLUS Timberlake

  • Weighted AverageYou have two types of coins: pennies and quarters. The pennies have a mass of 5g. The quarters have a mass of 15g. 57% of the coins are pennies, 43% of the coins are quarters. What is the average mass of your coins? *

  • Weighted Average Atomic MassYou have two isotopes of Boron: 10B and 11B. The 10B has a mass of 10amu. The 11B has a mass of 22 amu. 57% of the atoms are 10B, 43% of the atoms are 11B. What is the average mass of your atoms? *

  • LecturePLUS Timberlake*Example of an Average Atomic MassCl-35 is about 75.5 % and Cl-37 about 24.5% of natural chlorine. 35 x 75.5 = 26.4 100 35.5 37 x 24.5 = 9.07 100

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Problem AT6Using the periodic table, specify the atomic mass of each element (round to the tenths place):A.calcium________ B. aluminum________ C. lead________D. barium________E. iron________

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Solution AT6Using the periodic table, specify the atomic mass of each element (round to the tenths place):A.calcium_40.1 amu _ B. aluminum_27.0 amu _ C. lead_207.2 amu_D. barium_137.3 amu_E. iron_55.8 amu__

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Calculating Atomic MassAdd :Percent (%) abundance of each isotopeMultiplied by the Mass of each isotope of that element

    Weighted average = mass isotope1(%) + mass isotope2(%) +

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Atomic Mass of Magnesium Isotopes Mass of Isotope Abundance 24Mg =24.0 amu 78.70%

    25Mg = 25.0 amu 10.13%

    26Mg = 26.0 amu 11.17%

    Atomic mass (average mass) Mg = 24.3 amu Mg24.3

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Learning Check AT7Gallium is a metallic element found in small lasers used in compact disc players. In a sample of gallium, there is 60.2% of gallium-69 (68.9 amu) atoms and 39.8% of gallium-71 (70.9 amu) atoms. What is the atomic mass of gallium?

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Solution AT7Ga-69 68.9 amu x 60.2 = 41.5 amu for 69Ga 100Ga-71 (%/100)70.9 amu x 39.8 = 28.2 amu for 71Ga 100

    Atomic mass Ga = 69.7 amu

    LecturePLUS Timberlake

  • LecturePLUS Timberlake*Finding An Isotopic MassA sample of boron consists of 10B (mass 10.0 amu) and 11B (mass 11.0 amu). I

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