Download Use a Periodic Table to find the atomic mass and the atomic number

Chemistry
Atomic Structure Worksheet
Name__________________________
Date___________________________
Use a Periodic Table to find the atomic mass and the atomic number of each stable,
uncharged element in the table. Then fill in the correct number of protons, neutrons, and
electrons. (HINT: Remember that the atomic number is the number of protons which, in an
uncharged atom, is also equal to the number of electrons. The atomic mass is the sum of the
protons and neutrons, so to find the number of neutrons, subtract the atomic number from
the atomic mass.)
Element
Symbol
Element
Name
Atomic
Number
Atomic
Mass
# of
Protons
# of
Neutrons
# of
Electrons
H
He
C
N
O
F
Ne
Na
Mg
Al
Cl
K
Ca
Fe
Cu
Ag
Au
Pb
U
Ions are charged atoms. A positive charge means there are more protons than electrons.
A negative charge means there are more electrons than protons. Remember that the
proton number cannot change without changing the element; so ions are formed by a loss
or gain of electrons since proton number always remains the same. Tell how many
electrons the following ions have.
Na+1 _________
Cl—1 _________
O—2 _________
Al+3
_________
Ca+2 _________
N—3
Pb+4 _________
F—
_________
_________
Isotopes are different forms of the same element which have a different number of
neutrons than protons. Give the number of neutrons that the elements below must have in
order to have the atomic masses that they have. Remember that the proton number
cannot change without changing the element; so isotopes are formed when an atom is
missing or has extra neutrons. The atomic mass is the sum of the protons and neutrons, so
to find the number of neutrons, subtract the atomic number from the atomic mass.
24
11Na _________
33
15P_________
16
6C_________
17
10Ne_________
15
8O _________
34
13Al _________
3
2H _________
30
16S _________
Element
Symbol
11
+2
4Be
12 —3
7N
5
2He
127 —
53I
40 +
19K
Element
Name
Atomic
Number
Atomic
Mass
# of
Protons
# of
Neutrons
# of
Electrons