Name __KEY_______________________________________ Date _______________ Period __________
Atoms and Elements
An atom is the smallest particle into which an element can be divided and still maintain the properties of that
element. All elements are made of atoms. So what’s an element? What makes one element different from
another? Let’s find out!
Vocabulary: First things first, let’s look at the structure of an atom. Look up definitions of the following
parts of an atom and record your findings below.
Proton: The positively charged
F
9-P
10-N
Particles in the nucleus of the atom.
Each proton has a mass of 1 amu,
Or Atomic Mass Unit
positively charged +
located in the nucleus
mass = ~ 1 amu
Diagram:
Proton
+
Neutron:
Nucleus
The other particles in the nucleus
that have no charge.
No charge – neutral
Located in the nucleus
Neutron
Electron Mass = ~ 1 amu
Electron:
At various distances from the nucleus.They have
Almost no mass: about 1/2000th of an amu
Negatively charged –
Located outside the nucleus (electron cloud)
Mass = ~ 0 amu
Atomic Number:
Number of protons in an atom
It is a whole number
Atomic Mass:
The mixed number that is given on the periodic table for each
element. It is the average mass of an atom of that element. When
rounded to the nearest whole number, it is equal to the number of
particles in the nucleus.
An average of the total mass of all particles inside an atom (p + n +
e)
Investigative Question: What makes each element unique?
For each of the elements listed below find the following information: element name, number of protons,
number of neutrons, number of electrons, atomic number, atomic mass, and number of energy levels. Use the
website: www.chemicalelements.com/ to get started.
Example: H
Element Name: Hydrogen
Number of Protons: 1
Number of Neutrons: 0
Number of Electrons: 1
Number of Energy Levels: 1
Atomic Number: 1
Atomic Mass: 1.00794 amu
Be
Element Name: Beryllium
C
Element Name: Carbon
Number of Protons: 4
Number of Protons: 6
Number of Neutrons: 5
Number of Neutrons: 6
Number of Electrons: 4
Number of Electrons: 6
Number of Energy Levels: 2
Number of Energy Levels: 2
Atomic Number: 4
Atomic Number: 6
Atomic Mass: 9.012182 amu
Atomic Mass: 12.0107 amu
Mg
Element Name: Magnesium
S
Element Name: Sulfur
Number of Protons: 12
Number of Protons: 16
Number of Neutrons: 12
Number of Neutrons: 16
Number of Electrons: 12
Number of Electrons: 16
Number of Energy Levels: 3
Number of Energy Levels: 3
Atomic Number: 12
Atomic Number: 16
Atomic Mass: 24.305 amu
Ca
Element Name: Calcium
Atomic Mass: 32.066 amu
Br
Element Name: Bromine
Number of Protons: 20
Number of Protons: 35
Number of Neutrons: 20
Number of Neutrons: 45
Number of Electrons: 20
Number of Electrons: 35
Number of Energy Levels: 4
Number of Energy Levels: 4
Atomic Number: 20
Atomic Number: 35
Atomic Mass: 40.078 amu
Atomic Mass: 79.904 amu
Conclusions…
Analyze the data you collected. What patterns do you see within each element (differences and similarities)?
Look at the number of protons, neutrons, electrons, etc. What do you notice when you compare the elements
to one another? Write your statements in the space below:
 Within an element:
# protons and electrons is always the same, same as atomic number
Atomic mass is roughly the same as protons + neutrons
More mass means more energy levels
 Comparing elements:
# of protons is different for every element, same for # of electrons, atomic #, mass
All elements in the same period have the same number of energy levels
 Answer the investigative question: What makes each element different?
Each element has a different number of protons