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2.7: Unit 2 Practice Problems

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    259620

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    Question 1. 

    Which subatomic particle(s) determine an atom's name?

    Answer

    protons and neutrons

    Which subatomic particle(s) determine an atom's mass?

    Answer

    protons and neutrons

    Which subatomic particle(s) determine an atom's charge?

    Answer

    electrons and protons

    Question 2.

    Write the symbol for each of the following ions:

    (a) the ion with a 1+ charge, atomic number 55, and mass number 133

    (b) the ion with 54 electrons, 53 protons, and 74 neutrons

    (c) the ion with atomic number 15, mass number 31, and a 3− charge

    Answer
    (a) 133Cs+1   (b) 127I-1  (c) 31P-3
     

    Question 3.

    How many protons, neutrons, and electrons are in the following?

    (a)   87Sr+2

    (b)   75As

    Answer
    (a) protons = 38     neutrons = 49    electrons = 36
    (b) protons = 33    neutrons = 42   electrons = 33
     

    Question 4.

    According to Bhor's model, how many electrons are in the 4th energy level?

    Answer

    # electrons = 2(4)2 = 32 electrons

    Question 5. 

    Give the electron configuration for Ge using quantum mechanical notation.  

    Answer

    1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p2

    Question 6. 

    Give the electron configuration for Lu using noble gas configuration.   

    Answer

    [Xe] 6s2 4f14 5d1

    Question 7. 

    Give the electron configuration for S-2 using quantum mechanical notation.  

    Answer

    1s2 2s2 2p6 3s2 3p6

    Question 8. 

    Which atom has the electron configuration: 1s22s22p63s23p64s23d104p65s24d2?

    Answer

    Zr

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