Isotope Quiz
Top Questions Missed
#1 Difficulty: Finding the number
of protons
You need to know:
Atomic NUMBER is the number of
P_____________________
Protons!
Atomic MASS is two things added
together: P_________ & N__________
Protons and neutrons!
Let’s try finding the number of
protons:
 In a nitrogen atom with a mass number of
14 and an atomic number of 7, the
number of protons is
 7 (the atomic number is the number of protons)
 In a sodium atom with a mass number of
23 and an atomic number of 11, the
number of protons is
 11 (the atomic number is the number of
protons)
#2 Difficulty: Finding the atomic
mass
You need to know:
Atomic NUMBER is the number of
P_____________________
Protons!
Atomic MASS is two things added
together: P_________ & N__________
Protons and neutrons!
Let’s try finding the atomic mass:
 In a nitrogen atom with a mass number of
7 neutrons and an atomic number of 7,
the atomic mass is
 14 (the atomic mass is the number of protons
and neutrons added together)
 In a sodium atom with 12 neutrons and an
atomic number of 11, the atomic mass is
 23 (the atomic mass is the number of protons
and neutrons added together)
#3 Difficulty: the particle found
in all atoms
You need to know:
The periodic table has a pattern of
increasing protons
Therefore, all atoms on the periodic
table must have protons
#4 Difficulty: finding which
isotope is the most abundant
 You need to know:
 The average atomic mass listed on the periodic table
is the average mass of all the known isotopes of an
element
 You round the average atomic mass to the nearest
whole number to find the most common isotope.
 Rounding refresher:
 If the number in the tenths place is less than 5, you
round down (23.4 would be rounded down to 23
because 4 is less than 5)
 If the number in the tenths place is 5 or more, you
round up (23.5 would be rounded up to 24 because it is
5 or more)
 For example, on the periodic table the average
atomic mass of nickel is 58.69. The most common
isotope of nickel is nickel 59.
Let’s find the most abundant
isotopes:
 Potassium has an average atomic mass of 39.30.
What is the most common isotope?
 Potassium-39
 Chlorine has an average atomic mass of 35.34.
What is the most common isotope?
 Chlorine-35
 Copper has an average atomic mass of 63.55.
What is the most common isotope?
 Copper-64
#5 Difficulty: Determining an
electron from pictures
 You need to know:
 In a 0 charged atom, the
number of electrons is the
same as the number of
protons
 You can look up the name
of an element using the
periodic table if you know
the number of protons
 You need to know which
parts represent the
electrons in the picture
An element with 4 protons is
called Beryllium
Quiz Correction Directions:
1.Take out a piece of blank paper.
2.Write your name and period # on
the top.
3.Write out 3 questions you missed.
4.Answer the 3 questions correctly.
5.Attach the quiz results to the
corrections and place it in the inbox.
6.Return the quiz to Mrs. Bertoson.