Name: __________________
Atomic Numbers and Mass Numbers
Study carefully the sketches of Bohr models for four atoms below:
A
B
1.
C
D
Based on these sketches, fill in this table:
Atom
A
B
C
D
2.
# Protons
# Neutrons
# Electrons
Atomic #
Mass #
The following atom is the same element as one of the above atoms. Which one is it?
How can you tell? ________________________________________________________
N: 7
3.
Atoms of the same element that have different mass numbers are called__________________________
4.
In each atom shown, how do the number of protons and the number of electrons compare? Why is this
important? _____________________________________________________________________________
______________________________________________________________________________________
5.
Here is a list of atomic numbers. Use it to identify the atoms shown above:
Hydrogen = 1
Carbon
Helium
=2
Nitrogen
=7
Atom B = ______________________________
Lithium
=3
Oxygen
=8
Atom C = ______________________________
Beryllium = 4
Fluorine
=9
Atom D = ______________________________
Boron
Neon
= 10
=5
=6
Atom A = ______________________________
Name: __________________
Fill in the blanks in the following table. Please keep in mind that the isotope represented by each space may NOT
be the most common isotope or the one closest in atomic mass to the value on the periodic table.
Atomic
symbol
Atomic
number
Protons
B
Neutrons
Electrons
Mass
number
6
11
24
31
37
39
29
89
35
43
100
207
Pb
102
70
89
225
6.) How many electrons does nitrogen have? _______________________
7.) How many protons does magnesium have? ______________________
8.) What is the atomic number of sodium? _______________________
9.) If an atom of oxygen has a mass number of 15 amu, how many neutrons does it have?
_________________
10.) If an atom of chlorine of has a mass number of 35 amu, then how many protons does
it have? ___________________ How many neutrons does it have?__________________
11.) An atom has a mass number of 27 amu and 14 neutrons. What is it?
______________________