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CHAPTER 7 BASIC I & II HOMEWORK

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Question 1

Which of the following statements are correct?
Hint given in feedback
Select one or more:
Correct
Correct


 

Explanation

Under certain circumstance particle behave like waves and waves behave as particles. 

 

Question 2

What is the energy in J of 1 photon whose frequency is 3.17 x 1014 hertz (cycles per second)? Use scientific notation.

Correct

 

Explanation


 E = hf 
h = Planck's constant = 6.63 * 10^-34 Js 

E = (6.63 * 10^-34 Js)( 6.24 x 1014 hertz) = 2.10E-19 J
 

Question 3

What is the frequency in Hz (hertz) of visible light whose wavelength is 637 nm? a nm = 10-9m. Use scientific notation.

Help: frequency

Additional help in feedback

Correct

 

Explanation

 f = c /  λ


c= 3E8 m/s


f = (3E8 m/s)/  (637E-9 m) = 4.71E14


 

Question 4

Match properties correctly.

Help: Electron orbitals

l=3 Correct
Indicates energy and size of orbital Correct
l=2 Correct
Number of possible electron spins for each orbital Correct
l=0 Correct
l=1 Correct

 

Explanation

 

Question 5

Exciting an electron to an orbital with higher principle quantum takes energy. Which of the following excitation requires the most energy for the H atom?


Select one:
Correct

 

Explanation

 E = hf

E = hc/ λ 


The smaller the wavelength the greater the energy

 

Question 6

Correctly match the information for the angular momentum quantum number (l) which gives the shape of the orbital.

Orbital shaped like flower or fancy--3 nodal planes Correct
Spherically symmetric orbital--no nodal planes Correct
The maximum number of electrons in an electron orbital. Correct
Orbital shaped like a peanut or dumbbell--one nodal plane Correct
4 of the 5 orbitals shaped like a double peanut--2 nodal planes Correct

 

Explanation

  

 

Question 7

If n = 3, what are the allowed values of l?
Select one or more:
Correct
Correct
Correct

 

Explanation

 

Question 8

If n = 2, what are the allowed values of l?
Select one or more:
Correct
Correct

 

Explanation

 

Question 9

Match the number of orbitals for s, p, d, and f orbitals.
5d Correct
5s Correct
5f Correct
5p Correct

 

Explanation

 

Question 10

Which of the following are allowed spins for an electron in an orbital?
Select one or more:
Correct
Correct

 

Explanation

Electrons can spin only in positive and negative 1/2 directions

 

Question 11

Select the correct set of quantum mechanical numbers for an electron in an s, p, d, and f orbital. (4 correct answers.)

Help: Allowed quantum numbers

Select one or more:
Correct
Correct
Correct
Correct

 

Explanation


  

 

Question 12

Match the electron orbital with its energy.


Orbital lowest in energy Correct
Orbital 2nd lowest in energy Correct
Orbital 3rd lowest in energy Correct
Orbital 4th lowest in energy Correct
Orbital 5th lowest in energy Correct
Orbital 6th lowest in energy Correct
Orbital 7th lowest in energy Correct

 

Explanation

 

Question 13

For a ground state electron configuration, what is the next electron orbital to fill after the following orbitals have electrons in them?

1s 2s 2p 3s 3p 4s

Help: Order of orbital filling

 

Explanation

 

Question 14

What is the ground state electron configuration of B?
For F, 1s22s22p5, write 1s22s22p5 or 1s2 2s2 2p5.

 

Explanation

 

Question 15

What is the ground state electron configuration of Na?

 

Explanation

 

Question 16

What is the ground-state electron configuration for S?

Select one:
Correct

 

Explanation

 

Question 17

What is the ground state electron configuration for S2-?
Select one:
Correct

 

Explanation

 


with -2 charge (we add 2 electrons) :   

 

Question 18

What is the ground state electron configuration for K1+?
Select one:
Correct

 

Explanation

 Orginal: 1s22s22p63s23p 6 4s1


With +1 charge (we remove electron from highest energy level) 

1s22s22p63s23p 6

 

Question 19

What is the abbreviated or short-hand ground state electron configuration for Al? For Sc it is [Ar]4s23d1, for Moodle write [Ar]4s23d1 or [Ar] 4s2 3d1.

 

Explanation

[Ne] includes the electron configuration up to the noble gas Ne.

So everything after it is: 3s23p1


 

Question 20

What is the abbreviated or short-hand ground state electron configuration for Br?

 

Explanation

[Ar] includes the electron configuration up to the noble gas Ar.

So everything after it is: 4s23d104p5

 

Question 21

Which of the following electron configurations is correct for the ground state of O?
Select one:
Correct

 

Explanation

  

 

Question 22

Which of the following electron configurations is correct for the ground state of P?
Select one:
Correct

 

Explanation

 

Question 23

How many unpaired electrons are in the ground state electron configuration for Mn?

 

Explanation

There are 5 unpaired electrons in the d orbital 

 

Question 24

How many unpaired electrons are in the ground state electron configuration for Fe?

 

Explanation

There are 4 unpaired electrons in the d orbital 

Question 25

 

Gamma rays are electromagnetic radiation of very short wavelength emitted by the nuclei of radioactive elements. A certain radioactive element emits a gamma ray with a frequency of 1.39 x 10 20  Hz.  Express the wavelength of this radiation in picometers. (1Hz = 1 s-1 and 1 picometer = 1E-12 m) 

Correct

 

Explanation

λ= c / f


c= 3E8 m/s


λ(3E8 m/s)/  (1.39 E 20) = 2.16 E-12 = 2.16 pm

Question 26

 

The photoelectric effect for a certain alloy has a threshold frequency of  9.20 x 10 14 Hz. For light of this frequency, find the energy of one mole of photons (in kJ).

Hint given in feedback
Correct

 

Explanation

E = h f  x  ( # photons) / 1000

E = (6.63E-34)(9.20E14)(6.02E23) / 1000 = 367 

Question 27

 

Electrons are ejected from sodium metal by any light that has a wavelength shorter than 544 nm. What is the kinetic energy of an electron (in J) that is ejected from sodium by light with a wavelength of 213 nm? 

Correct

 

Explanation

E = (hc/ λ) - (hc/λ)


E = [ (3E8 x 6.63E-34)/ (544 E-9) ] - [ (3E8 x 6.63E-34)/ (213 E-9) ]

E = 5.68E-19

Question 28

 

The charge of an electron is -1.602 x 10 -19 C. For the photoelectric effect, how many microamperes (1 A = 1 C/s) of electrical current are produced when a metal is bombarded by 5.30x10 13 photons each second? Assume that each photon has sufficient energy to eject one electron. (Note currents are reported as positive values.) 

Hint given in feedback
Correct

 

Explanation

E = (photon charge) x (number of photons) / (1E-6)

E =  (1.602 x 10 -19 C ) x ( 5.30x10 13) / (1E -6) = 8.49 mA