Name______________________________ Period__________________________
WS4.4
Isotopes, ions, atomic mass, and average atomic mass worksheet The number of protons, electrons, and neutrons is usually symbolized in an element box in the following manner: For example: 235 41 Mass number
19
(p + + n 0) 24
Charge (p + + e -)
9
Na+
F-
2+
Ca
20
U
92
11
9 protons 10 neutrons 10 electrons
atomic number (p + )
20 protons 21 neutrons 18 electrons
92 protons 143 neutrons 92 electrons
Once the number of each atomic particle is known, it is an easy matter to identify isotopes (atoms that vary only in the number of neutrons) or ions (atoms that do not have the same number of protons and electrons). 1. Fill in the blanks
34
35
16
17
S
___protons ___ neutrons ___electrons
Cl
-
238
6+
U
92
___protons ___protons ___ neutrons ___ neutrons ___electrons ___electrons
32
35
238
16
17
92
S
Cl
4+
U
___protons ___ neutrons ___electrons
___protons ___protons ___ neutrons ___ neutrons ___electrons ___electrons
7 protons 9 neutrons 8 electrons
105 protons 8 protons 132 neutrons 8 neutrons 106 electrons 8electrons
2. Which pairs of elements are isotopes?
3. Which elements are ions? 4. Fill in the boxes below.
1 protons 0 neutrons 1 electron
23 protons 24 neutrons 22 electrons
5 protons 6 neutrons 8 electrons
19