# CHEM125 – CHAPTER 07 – BASIC I & II HOMEWORK

## CHAPTER 07 BASIC I & II HOMEWORK

### Resources:

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### Question 1

Which of the following statements are correct? Hint given in feedback Help: Dual nature–particle or wave Select one or more:

### 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. Help: Energy of waves

### 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

### 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=3Choose…nfpds2 Indicates energy and size of orbitalChoose…nfpds2 l=2Choose…nfpds2 Number of possible electron spins for each orbitalChoose…nfpds2 l=0Choose…nfpds2 l=1Choose…nfpds2

### 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:

### 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. Help: Angular momentum quantum No. Orbital shaped like flower or fancy–3 nodal planesChoose…2fspd Spherically symmetric orbital–no nodal planesChoose…2fspd The maximum number of electrons in an electron orbital.Choose…2fspd Orbital shaped like a peanut or dumbbell–one nodal planeChoose…2fspd 4 of the 5 orbitals shaped like a double peanut–2 nodal planesChoose…2fspd

### Question 7

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

### Question 8

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

### Question 9

Match the number of orbitals for s, p, d, and f orbitals. Help: Electron orbital details 5dChoose…3 orbitals7 orbitals1 orbital5 orbitals 5sChoose…3 orbitals7 orbitals1 orbital5 orbitals 5fChoose…3 orbitals7 orbitals1 orbital5 orbitals 5pChoose…3 orbitals7 orbitals1 orbital5 orbitals

### Question 10

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

### 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:

### Question 12

Match the electron orbital with its energy. Help Multielectron orbital energy Orbital lowest in energyChoose…1s (1 orbital; max of 2 electrons)3p (3 orbitals; max of 6 electrons)2p (3 orbitals; max of 6 electrons)4s (1 orbital; max of 2 electrons)2s (1 orbital; max of 2 electrons)3s (1 orbital; max of 2 electrons)3d (5 orbital; max of 10 electrons) Orbital 2nd lowest in energyChoose…1s (1 orbital; max of 2 electrons)3p (3 orbitals; max of 6 electrons)2p (3 orbitals; max of 6 electrons)4s (1 orbital; max of 2 electrons)2s (1 orbital; max of 2 electrons)3s (1 orbital; max of 2 electrons)3d (5 orbital; max of 10 electrons) Orbital 3rd lowest in energyChoose…1s (1 orbital; max of 2 electrons)3p (3 orbitals; max of 6 electrons)2p (3 orbitals; max of 6 electrons)4s (1 orbital; max of 2 electrons)2s (1 orbital; max of 2 electrons)3s (1 orbital; max of 2 electrons)3d (5 orbital; max of 10 electrons) Orbital 4th lowest in energyChoose…1s (1 orbital; max of 2 electrons)3p (3 orbitals; max of 6 electrons)2p (3 orbitals; max of 6 electrons)4s (1 orbital; max of 2 electrons)2s (1 orbital; max of 2 electrons)3s (1 orbital; max of 2 electrons)3d (5 orbital; max of 10 electrons) Orbital 5th lowest in energyChoose…1s (1 orbital; max of 2 electrons)3p (3 orbitals; max of 6 electrons)2p (3 orbitals; max of 6 electrons)4s (1 orbital; max of 2 electrons)2s (1 orbital; max of 2 electrons)3s (1 orbital; max of 2 electrons)3d (5 orbital; max of 10 electrons) Orbital 6th lowest in energyChoose…1s (1 orbital; max of 2 electrons)3p (3 orbitals; max of 6 electrons)2p (3 orbitals; max of 6 electrons)4s (1 orbital; max of 2 electrons)2s (1 orbital; max of 2 electrons)3s (1 orbital; max of 2 electrons)3d (5 orbital; max of 10 electrons) Orbital 7th lowest in energyChoose…1s (1 orbital; max of 2 electrons)3p (3 orbitals; max of 6 electrons)2p (3 orbitals; max of 6 electrons)4s (1 orbital; max of 2 electrons)2s (1 orbital; max of 2 electrons)3s (1 orbital; max of 2 electrons)3d (5 orbital; max of 10 electrons)

### 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

### Question 14

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

### Question 15

What is the ground state electron configuration of Na?

### Question 16

What is the ground-state electron configuration for S? Help: Using the periodic table to get the ground state Select one:

### Question 17

What is the ground state electron configuration for S2-? Help: Ground state for negative ion Select one:

### Explanation

with -2 charge (we add 2 electrons) :

### Question 18

What is the ground state electron configuration for K1+? Help: Ground state for positive ion Select one:

### 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. Help: Abbreviated notation

### 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? Help: Electron configuration including spin Select one:

### Question 22

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

### 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)

### 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

### 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?

### 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 5.30×10 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

### Explanation

E = (photon charge) x (number of photons) / (1E-6) E = (1.602 x 10 -19 C ) x ( 5.30×10 13) / (1E -6) = 8.49 mA