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Name_______________________ Hr_____
Atom, Ion, Isotope Homework
1. What is the name of the element that has
atoms that contain 25 protons.
manganese
7. Write the complete chemical symbol for
the ion with 84 protons, 125 neutrons, and
80 electrons. 209Po-4
2. Write the chemical symbol for the ion
with 19 protons and 18 electrons (show
charge).
K+1
8. Write the complete chemical symbol
for the ion with 27 protons, 32 neutrons,
and 25 electrons. 59Co+2
3. Write the chemical symbol for the ion
with 7 protons and 10 electrons (show
charge). N-3
9. How many protons, neutrons, and
3+
electrons are present in the 140
58 Ce ion?
P=58 N=82 e = 55
10. Write the complete chemical symbol for
the ion with 73 protons, 108 neutrons, and
68 electrons.
181Ta+5
11. How many protons, neutrons, and
2electrons are present in the 45
21 Se ion?
P=21 n=24 e=23
12. Write the complete chemical symbol for
the ion with 31 protons, 39 neutrons, and 28
electrons.
70Ga+3
4. Write the chemical symbol for the ion
with 9 protons and 10 electrons (show
charge). F-1
5. Write the chemical symbol for the ion
with 20 protons and 18 electrons (show
charge).Ca +2
6. How many protons, neutrons, and
2+
electrons are present in the 59
28 Ni
ion?
P=28 n=31 e=26
13. Fill in the table.
Sub-atomic
Location
Particle
Proton
Nucleus
Mass (amu)
Charge Role
1
+1
Identity, atomic no.
Neutron
Nucleus
1
0
Holds nucleus together
Electron
Orbiting around
nucleus
~0
-1
reactivity
14. What is mass number? What particles are involved? How?
Protons + neutrons
15. What is charge? What particles are involved? How?
Protons - electrons
16. Calculating Average Atomic Mass
Elements come in a variety of isotopes, meaning they are made up of atoms with the same
atomic number but different masses. These atoms differ in the number of neutrons.
The average atomic mass is the weighted average of all the isotopes of an element.
Work through the guided example and then find the average atomic mass for (a) – (d)
below. Show your work for credit.
Guided Example: A sample of cesium has three isotopes present: cesium-132, cesium-133 and cesium134. The percent abundances are 20%, 75% and 5%, respectively. Find the average atomic mass.
1. Organize this information into a table.
Percent Abundance
Decimal Equivalent
Isotope Mass Number
20
0.20
132
75
0.75
133
5
0.05mass of the following134
Determine
the average atomic
mixtures of isotopes. Show your work for
Check and make sure your decimal equivalents sum to 1. If not, there is an error!
each.
2. Fill in the blanks and calculate the average atomic mass:
0.20(132) + 0.75 (__133__) + _0.05____ (134) = ___132.85________
a.
80%127I,
17%126I ,
3%128I
.8*127 + .17*126 + .03*128 = 126.86
b. 4.35% 50Cr, 83.8% 52Cr,
9.5% 53Cr,
2.35% 54Cr
0.0435*50 + .838*52 + .095*53 + 0.0232*54 = 52.0388
c.
78.7% 24Mg, 10.13% 25Mg,
d.
95% 14N, 3% 15N,
11.17% 26Mg
2% 16N
19. How many protons and neutrons are in titanium-46?
P=22 n=24
p=7, n=8
Nitrogen-15?
Sulfur-34?