1. An electron with a mass of 9.11x 1 0 -31 kg has a velocity of 2.19x 1 0 6 m/s

Question

1. An electron with a mass of 9.11x10-31 kg has a velocity of 2.19x106 m/s in the innermost orbit of a hydrogen atom. What is the de Broglie wavelength of the electron?

7.   An electron making a standing wave in a hydrogen atom has a wavelength of 6.65x10-10m. What is the speed of the electron according to the de Broglie equation?

12. Identify the number of protons, neutrons, and electrons in the following isotopes:

                  b. 7Li                            d. 48Ca                            e. 235U    

19. Use chemical symbols and numbers to identify the following isotopes:

b. Neon-22                   c. Tungsten-184     

21. Give the number of protons and the number of neutrons in the nucleus of the following isotopes.

      a. Aluminum-25            b. Technetium-95             c. Tin-120            d. Mercury-200

22. Write the chemical symbols for each of the nuclei in exercise 21.

Explanation / Answer

here,

1)

mass, m = 9.1 * 10^-31 kg

v= 2.19 * 10^6 m/s

lamda = h/mv

lamda = 6.626 * 10^-34 /( 9.1 * 10^-31 *2.19 * 10^6 )

lamda = 3.32 * 10^-10 m

the debroglie's wavelength is 3.32 * 10^-10 m

7)

wavelength , lamda = 6.65 * 10^-10 m

the speed of the electron according to the de Broglie equation , v = h /( m * lamda)

v = 6.626 * 10^-34 /( 9.1 * 10^-31 * 6.65 * 10^-10)

v = 1.09 * 10^6 m/s

the speed of the electron according to the de Broglie equation is 1.09 * 10^6 m/s

12 a)

For LI7
Number of protons = 3
Number of electrons = 3
Number of neutrons = 4

12 b)

For 48 Ca

neutrons = 28

protons = 20

electrons = 20

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