Chemistry REVIEW: Chapter 3 & 22
Name: ____KEY____________________
1. What is an isotope?
2. What is an ion?
3. How can atoms become a cation?
4. How can atoms become an anion?
5. A particle of oxygen that contains 8 protons & 8 electrons.
Circle ONE a) Charge: Positive Negative or No charge
b) Is this an atom or ion? ATOM
6. A particle of fluorine that contains 9 protons & 10 electrons.
Circle ONE a) Charge: Positive Negative or No charge
b) Is this an atom or ion? ION = ANION
7. A particle of calcium that contains 20 protons & 18 electrons.
Circle ONE a) Charge: Positive Negative or No charge
b) Is this an atom or ion? ION = CATION
8. You may use the following answers MORE than once:
A) Isotope
E) electron
B) Atomic Number
F) Neutron
C) Atomic Mass Number
G) Nucleus
___D___ 1) has a positive charge
___G___ 2) where the proton is found
___C___ 3) is the sum of the neutrons and the protons
___A___ 4) an element with different number of neutrons
___F___ 5) has no charge
___G___ 6) where the neutron is found
___E____ 7) is the lightest particle
___E___ 8) has a charge of -1
___H___ 9) Elements with different number of electrons
___B___ 10) The number of protons in an element
___D___ 11) Particle that distinguishes the elements from one another
___E___ 12) Particle found outside the nucleus
d) Proton
h) Ion
91
9. Give the number of protons, neutrons and electrons in 40Zr +4 ion
Protons: ___40_____
Neutrons: ____51_____
Electrons: ____36______
10. Complete the following table
Hyphen
Notation
the atom that contains 10 protons and 11 neutrons
Ne-21
the ion that contains 16 protons, 17 neutrons and 18 electrons
S-33 -2
the ion that contains 56 protons, 54 electrons and has a mass# of
141
Nuclear
Notation
Ba-141 +2
11. Compare the density and charge of the nucleus and the electron cloud.
Nucleus has a POSITIVE charge & is extremely dense.
Electron cloud has NEGATIVE charge & is mostly space
12. What is “average atomic mass”?
13. The mass of element X has a 78.99% abundance for isotope 23.9850, 10.00% for isotope
24.9858 and 11.01% for isotope 25.9826.
a) What is the atomic mass of the element? __24.305_________
(Hint: Calculation is based on a weighted average.)
b) What element is it? ___MAGNESIUM__________
14. How many atoms are there in 2.50 mol of Hydrogen?
1.51 x 10 24 atoms Hydrogen
15. How many moles are present in 107 g of sodium?
4.65 moles Na
16. How many atoms are in 80.45g of magnesium?
1.99 x 10 24 atoms Mg
17. Be sure you understand the following concepts before the test:
Law of Conservation of Mass
Law of Definite Proportions
Law of Multiple Proportions
Chapter 22 REVIEW
18. Radiation is an unstable nucleus that spits out particles from the _NUCLEUS_______.
19. What cause the nucleus to be unstable? _______________________________.
20. a) Do different atoms of the same element have different half-life (t ½ )? NO
Different atoms of the same element have the SAME half-life.
b) Do different isotopes have different half-lifes (t ½ )? YES
Different isotopes have a different neutron number which results in different half-life
21. List THREE Nuclear Applications
1. _______________________ 2. ______________________ 3. _______________________
22. Why is it important to know the “mass defect” number?
Missing mass is converted into energy.
Nuclear power plants create only enough energy to produce electricity.
(Too much energy would result in atomic bombs.)
23. Explain the difference between Nuclear Fusion and Nuclear Fission and give an example of
each.
24. Write balanced nuclear equations for the following transformations.
a. neodymium-141 undergoes electron capture
Pr-141
b. selenium-81 undergoes beta decay
Br-81
c. strontium-83 decays by positron emission
Rb-37
25. What particle is produced during the following decay processes? (Alpha, Beta, Gamma, etc).
a. Na-24 to Mg-24
________________________________ BETA
b. Hg-188 to Au-188 ________________________________
POSITRON
c. I-122 to Xe-122
________________________________
BETA
d. Pu-242 to U-238
________________________________
ALPHA
26. Complete and balance the following nuclear equations by supplying the missing particle.
a. 252Cf +
10B
1
 3 0n + ______
c. 59Fe  β + _______
f. 88Sr +
84Kr
 116Pd + _______
b. 122I 122Xe + _______
d.
233U
1
+ 0n  133Sb +
d. 40Ca + 238U 
70Zn
98Nb
1
+ _______ 0n
1
+ 4 0n + 2 _______
27. A radioactive decay series that begins with Th-232 ends with the formation of the stable
nuclide Pb-208. How many alpha-particle emissions and how many beta-particle emissions are
involved in the sequence of radioactive decays?
alpha = __6____ beta = __4___
28. The half-life of tritium (hydrogen-3) is 12.3 years. Suppose 48.0mg of tritium is released from a
nuclear power plant during the course of an accident.
a. What mass of this nuclide will remain after 12.3 years?
24 mg
b. What mass will remain after 49.2 years?
3 mg
29. It takes 5.2 minutes for a 1.000g sample of 210Fr to decay to 0.250g. What is the half-life of
210Fr?
2.6 min
30. Cobalt-60 has a half-life of 5.26 years. The Co-60 in a radiotherapy unit must be replaced when
its radioactivity falls to 75% decay. If the original sample was purchased in August 2007, when
will it be necessary to replace the Co-60?
T = 10.52 year
Aug 2007 + 10.52 yrs = February 2018