UNIT 2 REVIEW
Concepts: Dalton’s atomic theory, chemical formula, parts of an atom (proton, electron,
neutron), nucleus, isotopes, atomic #, mass #, ion, diatomic molecule, ionic compound, periodic
table
1. Draw the atom symbol for Europium with a mass number of 155. 
2. How many protons do each of the following atoms have
(a little element practice while you’re at it)?
Tungsten ____
Ra_____
Manganese _____ Tin_____
Iron____
Br _____
S____
Barium ____
3. Fill out the table with all of the missing information:
Symbol
Atomic number
Mass number
79
185
Protons
Neutrons
Electrons
V
49
79
18
24
18
230
90
92
100
44
41
Pb4+
210
48
S
31 2-
65
45
4. Using the following symbols, tell how many protons, neutrons and electrons in each:
140
+
94
200
La
Which of the above are IONS?
Zr
+2
Hg
Which are ATOMS?
How do you know?
5. Complete the following chart:
Isotope name
atomic #
mass #
# of protons
# of neutrons
# of electrons
uranium-235
uranium-238
boron-10
boron-11
What do U-235 and U-238 (or B-10 and B-11) have in common? What are they called?
6. Draw an element symbol of a Cesium ion
that has 75 neutrons and 56 electrons
