Name: ANSWER CHECK
Date:
Period:
Unit 3 Study Guide
EM Spectrum, Electron Configurations, Periodic Trends
Electrons absorb energy
to jump energy levels.
EM Spectrum
By using the Bohr model of a Hydrogen atom to the left, answer the following
questions.
1. Light (photons) will be given off by an atom when the electrons fall back to
the ___ ground_____ _ state.
2. For an electron to move from the ground state to the excited state energy
must be
absorbed
.
Look at the model of a wave of light to answer the question 3 and 4.
Electrons release energy as light or
photons when they fall back down
to their ground state.
3. What is a bundle or packet of energy in a light wave called? photon
4. What 2 characteristics does electromagnetic radiation have that describes
how it moves through space? (Think about the wave machine.)
Light acts as both a wave and particles as it moves through space.
Wavelength of light
Photons – Bundles of
energy in a wave of light.
5. Write the term that each of the following symbols stand for & include the proper units:
E = Energy, (J) joules
λ = wavelength, (m) meters
c = speed of light, (m/s) meters/second ν = frequency, (Hz) hertz, or (1/s)
h = plank’s constant, (Js) Joules x second
(1 meter = 1 x 109 nm) (1 MHz = 1 x 106 Hz)
6. Write the equation for the speed of light. c = λ v
7. What is the value for the speed of light (c)? (Remember: All light travels at the same speed)!
3.0 x 108 m/s
8. Write the equation for the energy of a wave of light.
E = hv
9. What is the value for Plank’s constant (h)?
h = 6.626 x 10-34 Js
Solve the following EM wave problems using the information you found above.
10. In the emission spectrum of Argon, there is a green band with a wavelength of 5.55 x 10-7 m. What is the energy of
the wave?
(1) Use the speed of light equation to find the frequency of the green light with the given wavelength.
(2) Once the frequency is found, plug it into the energy equation to find the energy of the wave.
11. What is the wavelength of a wave with a frequency of 120.8 MHz?
(1) Change the value of the given frequency from mega hertz (MHz) to Hertz (Hz). Use the following conversion
factor to change the units. (1 MHz = 1 x 106 Hz)
(2) Use the speed of light equation to find the wavelength. Plug into the equation the frequency in Hertz.
Name: ANSWER CHECK
Date:
Period:
12. A spectral line with 7.75 x 10-19 J of energy is produced when electrons of sodium release energy. What is the
frequency of this photon?
(1) Use the energy equation to find the frequency of the wave. Plug into the equation the given energy.
13. A photon has a wavelength of 4.40 x 10-7 m. What is the color of the photon?
(1) Change the given wavelength from meters (m) to nanometers (nm). Use the following conversion factor to change
the units. (1 meter = 1 x 109 nm)
(2) Find the wavelength in nanometers that you calculated on the
visible light diagram and ID the color of the wavelength.
Electron Configurations
14. Fill in on the blank P.T where the s, p, d, and f orbitals are
represented.
S
p
d
f
15.
16.
17.
18.
How many energy levels of electrons are there? (How many rows are there on the P.T?) ___7_____
How many types of orbitals are there?
4
How many electrons can each of the orbitals hold? s = 2
p=6
d = 10
f = 14
Draw the shape of each type of orbital
underneath the letter.
19. How many electrons can energy level 2 hold? (How many total electrons are in energy level 2?)
8
20. Write the electron configuration for the following elements. (You may use the short hand electron configuration).
a) K = 1s22s22p63s23p64s1 b) Rb = 1s22s22p63s23p64s23d104p65s1 c) Ag = 1s22s22p63s23p64s23d104p65s24d9
d) S = 1s22s22p63s23p4
e) As = 1s22s22p63s23p64s23d104p3
f) Sc = 1s22s22p63s23p64s23d1
21. Identify the element from the given electron configuration.
a. 1s22s22p63s23p2 ___Nitrogen (N)
b. [Ar]4s23d104p3 ___Arsenic (As)
c. [Kr] 5s24d105p2
Tin (Sb)
Periodic Table Trends
Consider the elements Nitrogen (N), Potassium (K), Bromine (Br), and Fluorine (F).
21.
22.
23.
24.
25.
a.
Which element has the highest electronegativity? ____Fluorine______________
Which element has the smallest ionization energy? ____Potassium______________
Which element has the largest atomic radius? _____Potassium_____________
Will sodium be smaller or larger when it ionizes? ____smaller because it becomes a cation__________
Circle the ion or element in the given pair that has the largest radius.
Fe2+ Fe
b. N N-3
c. As As-3
d. Ca Ca2+
26. Write each of the three elements in order from SMALLEST to LARGEST electronegativity.
a. lithium, potassium, sodium
K, Na, Li, or (potassium, sodium, lithium)
They go in this order from smallest to largest because element become more electronegative at you go to the top and to
the right on the periodic table.