1.Each metal in fireworks display produces a characteristic color. What are the

Question

1.Each metal in fireworks display produces a characteristic color. What are the frequency and color associated with each of the following.

(a) Cs+, ? = 456 nm

frequency =     s-1

(b) Ba2+, ? = 551 nm

frequency =     s-1

(c) Na+, ? = 590 nm

frequency =     s-1

2.The laser light used in compact disc players has a wavelength of 780 nm. In what region of the electromagnetic spectrum is this light?

3.What is the energy of this light? answer is in Joules

4.To "read" a feature, the wavelength of light must be less than half the feature size. How many features per millimeter of track can 780 nm light read?

6.Use the periodic table to decide how many core electrons are in each of the following: Ra, C, Br, and Ba.

7.How many electrons can have the following in common?

8.We encounter a large number of waves every day without realizing it. One such source is radio waves. A typical frequency for radio transmission is 685 kHz. How much energy does one mole of radio waves carry?

9.X rays used by doctors to view bones are much more energetic than radio waves. Determine the energy of one mole of X ray photons (3.8 ? 1017 Hz). answer is in J/mol

Explanation / Answer

1) f = (2.9979x10^8m/s)/(456x10^-9m) = 657.434 sec^-1

this is blue

2) f = 2.99*10^8/551*10^-9 m = 544.64 sec^-1

pale apple green color

3) d) f = (2.9979x10^8m/s)/(589x10^-9m) = 508.98 sec^-1

this is orange

2) IR region

3) E = hv = 6.625*10^-34*3*10^8/780*10^-9 = 0.025*10^-17 J

4)10^6 features

6) Ra ..... 86
C ........ 2
Br....... 28
Ba ....... 56

7)
a) 6g ........... 18 e-
b) 5f ............ 2e=
c) 6f ............... 14e-
d) 4d .................. 10 be-

8) E= hv = 6.625*10^-34*685*10^3 = 4.538 *10^-28 J

9) E= hv = 6.625*10^-34*3.8*10^17 = 2.517*10^-16 J

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