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Name_______________________________________________period________Unit 3 worksheet
1.
2.
3.
An atom has a mass number of 43 and it also has 21 electrons.
a) How many protons does this atom have?
b) What is the identity of this atom?
c) How many neutrons does this atom have?
A neutral atom has 14 protons and 18 neutrons. Chooses the correct nuclear symbol for this atom.
a) 3218Ar
b)3214 Si
c)1814 Si
d. 1432 Ge
Which of the following pairs show two atoms with the same number of neutrons?
a) 3717Cl and 3818Ar
b)5927Co and 6127 Co
c) 3215P and 3216S
d)6530Zn and 6730Zn
4.
There are three stable isotopes of Argon: Argon-36, Argon-38, and Argon-40. What would the atoms of these isotopes have
in common? What would be different about their atoms?
5.
Write the nuclear symbol for an ion with 26 protons, 30 neutrons, and 23 electrons
6.
A certain ion has an atomic number of 16, a mass number of 33, and 18 electrons.
a) What is the charge on the ion?
b) What is the identity of this ion?
c) How many neutrons does the nucleus of this ion have?
7.
Tritium (an isotope of hydrogen) has 2 neutrons. How many protons does it have? What is its mass number?
8.
What is the charge on a magnesium ion that has 10 electrons?
9.
How many neutrons are there in a chromium atom with a mass number of 54?
10. Substance E has 29 protons, 28 electrons, and 34 neutrons. Substance F has 29 protons, 27 electrons, and 34 neutrons.
Substances E and F can be categorized as…
A) different elements
B) ions
C) isotopes
D) nuclides
E) nucleons
11. The element with 38 protons and 45 neutrons could correctly be identified as which element?
12. Complete the following table:
Symbol
# of neutrons
136
56
Ba
# of protons
# of electrons
25
25
Atomic #
Mass #
2
120
21
79
20
56
79
18
13. A certain element exists as three different isotopes. 24.1% of all the isotopes have a mass of 75.23 amu, 48.7% have a mass
of 74.61 amu, and 27.2% have a mass of 75.20 amu.
a) What is the average atomic mass of this element?
b) Use your periodic table to determine which element this is.
14. Calcium has three different isotopes. One has a mass of 35.00 amu; another has a mass of 41.00 amu; and another has a mass
of 40.00 amu. Which isotope is the most abundant of the three? (HINT: Look at the periodic table at calcium’s average
atomic mass.)
15. What one number identifies an element?
16. The atomic weight of magnesium is reported as 24.3 amu, yet no atom of magnesium has a mass of 24.3 amu. Explain.
17. Using the periodic table, write the hyphen notation for each isotope described
a) Atomic number = 2, mass number = 4
b) Atomic number = 19, mass number 39
18. Find the mass for each of the following (Show work)
a.
1.00 mol of Al
d. 6.75 mol lead
b.
6.02 x 10 23 atoms of Ag
e. 1 atom gold
c.
3.01 x 10 23 atoms of F
f. 1.38 mol Nitrogen
19. Find the number of atoms in each of the following (show work)
a.
1.50 mol Na
d. 0.025 kg platinum
b.
7.02 g Si
e. 6.50 mol copper
c.
4.5 x 10 5 mg B
f. 1.00 mol aluminum
20. Find the number of moles in each of the following (show work)
a.
40.1 g Ca
d. 152 g sulfur
b.
0.11 kg Na
e. 50.0 atoms barium
c.
2.25 x 10 25 atoms Zn
f. 26,500 mg iron
21. Where does most of the mass of an atom come from?
22. Where does most of the volume of an atom come from?
Review
23. Calculate and report with the correct number of significant figures
a. 0.0098 x 2.34
b. 45.6 – 41.1
24. What reacts similarly to barium?
25. Name a halogen.
26. Name the most reactive alkali metal.
27. Label as a metal, nonmetal, or a metalloid
a. Aluminum
b. silver
28. Convert
a. 45.6 cm3 to L
b.
0.098 kg to g
c. sulfur
d. boron
e. hydrogen
f. barium