What is the minimum frequency of light needed to eject

Question

1. The work function of potassium is 3.68 x 10^-19 J.

a. What is the minimum frequency of light needed to eject electrons from the metal?

b. Calculate the kinetic energy of the ejected electrons when light of frequency equal to 8.62 x 10¹⁴ s^-1 is used for irradiation.

2. Thermal neutrons are neutrons that move at speeds comparable to those of air molecules at room temperature. These neutrons are most effective in initiating a nuclear chain reaction among ²³⁵U isotopes. Calculate the wavelength (in nm) associated with a beam of neutrons moving at 7.00 x 10² m/s (mass of neutron = 1.675 x 10^-27 kg)

3. The blue color of the sky results from the scattering of sunlight by air molecules. The blue light has a frequency of about 7.5 x 10¹⁴ Hz.

a. Calculate the wavelength. in nm. associated with this radiation

b. Calculate the energy, in joules, of a single photon associated with this freauency

4. When an intense beam of green light is directed onto a copper surface, no electrons are ejected. What will happen if the green light is replaced with red light?

5. The velocity of an electron that is emitted from a metallic surface by a photon is 3.6 x 10³ km.s^-1. What is the wavelength of the ejected electron?

6. Alarm systems employ the photoelectric effect. Typically, a light beam is aimed at a sample of Na, producing a photoelectric current. An intruder blocks the beam, thereby turning off the current, and triggering the alarm. Given that the work function of Na is 4.41 x 10^-19 J particle-1, what is the longest wavelength of light (in nm) that can be used in the alarm system?

7. A certain cation Xⁿ⁺ has an electron configuration of [Ar]3d⁵. Answer the following:

a) What type of element is X?

b) The reaction of X with chlorine gas proceeds as following:

2X_(s) + 3Cl_2(g) -> 2XCl₃(s)

Given this, determine n+

c) Now that you know the charge of the cation, determine the identity of X.

8. Draw the lewis dot structure give the molecular shape

Moleule	Lewis structure	Electronic geometry	Molecular geometry (shape)
SeH2

9. Give the full ground state electron configuration and the abbreviated noble gas) configuration for the following elements and or ions:

a) C  

b) Se²+     

c) Fe

d) P

e) Tc

f) Cr   

g) Cu  

h) Ho

g) Cr⁺

h) CI^-

10. Which of the following combinations of quantum numbers are allowed for an electron? Which are not? What would you change to make the ones that are not possible be possible?

a n=2 /=2 mi=1 ms =1/2

b.  n=3 1=1 mi=0 m_s =-1/2

c.   n=5 1=1 mi=2 ms =1/2

d.  n=4 /=-1 mi=0 ms =1/2

11. Label the orbital described by each of the following sets of quantum numbers

a. n=4 1=1 4 orbital_________

b. n=2 1=04 orbital_______

c. n=6 1=34 orbital_______

d. n=51=24 orbital

12. What are the principal (n) and orbital angular momentum (1) for each of the following:

a.  6p n =     l =

b. 3d n =      l =

c.  2p n =      l =

d.  5 f n =     l =

e. 2 s n =     l =

f. 6 f n =      l =

g. 4 d n =    l =

h. 5 p n =    l =

13. How many electrons can have the following quantum numbers in an atom:

a. n = 2,1=1

b. n = 5,1=3, m1=-1

c. n = 2,1=1, mi=0

d. n = 7

14. The 3 quantum numbers for an electron in a hydrogen atom in a certain state are n=4, 1=2, The electron is located in what type of orbital?