Interactive Lecture Resource Package
ESCI 350
Wesley de Leeuw
200284764
Periodic Table Trends
This lecture can be done in a regular classroom environment. There are a variety of ways to
portray the trends, my preferred methods are included in this document.
Ionization Energy:
 Ionization Energy is the energy it takes to remove electrons from an atom. Prior to
talking about this, students should know that the noble gases are stable elements because
of their electron configuration. When any atom becomes an ion, they do so to be like the
noble gases (you could say it’s because the noble gases are “cool”, whatever you would
like to give students a reason for this). Ask the students to look at Lithium. Identify the
two closest noble gases to lithium. They are Helium and Neon. In order to have an
electron configuration like Helium, Lithium will need to lose some electrons. In order for
it to have an electron configuration like Neon, Lithium will need to gain some electrons.
This is where the students come in.
 Have one student come up to the front of class, and tell them that they are the nucleus.
Ask the class how many valence electrons Lithium has (this should be already covered
when they covered electron configurations). Lithium has one valence electron, so bring
one additional student to the front. This student will act as the valence electron for
Lithium. Use questioning to have the class deduce that to become like Helium, Lithium
will need to lose one electron and to become like Neon, Lithium will need seven
additional electrons.
 Send the valence electron to go sit in their desk. Ask the class how much energy that
took. They will likely say not very much. Bring the student back up.
 Choose seven additional electrons, and have them all come up and try and find a space
around the nucleus. Now ask the class which took more energy, gaining electrons or
losing electrons. Students should be able to figure out that losing electrons was more
energy efficient. Label the energy it took for losing electrons as Ionization Energy. You
can do other examples with atoms like Boron, Oxygen, and Fluorine. Have the students
order those examples in order of which took more energy (all examples will need to be
from the same row of the periodic table). The trend students should make is that
Ionization Energy increases across the periodic table.
Electron Affinity/Electron Attachment:
Interactive Lecture Resource Package
ESCI 350
Wesley de Leeuw
200284764
 After covering Ionization Energy, do an example with Fluorine as the atom you want to
turn into an ion. It can be either like Helium or Neon. Run through the example as you
did with lithium, and students will learn that Ionization energy isn’t always the most
energy favourable. Label the process of gaining additional electrons as the Electron
Attachment energy.
 Do examples with atoms such as Sodium, Silicon, Aluminum, and Chlorine. Have
students put their Electron Attachment energies in order of lowest to highest, and point
out to the students that this isn’t the same trend as Ionization energy. Electron
Attachment energy decreases across the rows of the periodic table.
Size of the Atom:
 Write the elemental symbol for Sodium and Chlorine on the board. Ask the students to
identify how many protons, electrons, and neutrons are in each atom. Write this
information on the board. With that, pose a question to the students; which atom is going
to be bigger?
 The correct answer is that sodium will be the bigger atom. Ask students to explain their
answers. Chlorine is the more likely choice, because it has more things in it and is the
heavier atom.
 If you have magnets on hand, this is an interesting place to use them but only if you have
magnets that vary in strength. Tell your class that the charges on the nucleus can be
pictured as magnets. The Sodium nucleus has 11 protons, thus a +11 charge. The
Chlorine nucleus has 17 protons, thus a +17 charge. When thinking about things like
magnets, ask students what will be the stronger magnet and they should respond with
Chlorine. Take the stronger magnet, and identify it as a chlorine nucleus. Take
something that is easily attracted to magnets and set it close by. Try to do this
demonstration so that as many students as possible can see. With the stronger magnet, it
pulls it in quickly and tightly. The object can’t get far from the magnet.
 Now bring out the weaker magnet, and repeat the same procedure. Notice how close you
will need to bring the object to be attracted to the magnet. Once stuck to the magnet, you
can easily pull the object away.
 The valence electrons are simulated by the magnetic object, and when they are in their
shell they are more attracted to the strong magnet (Chlorine) than they are the weak
Interactive Lecture Resource Package
ESCI 350
Wesley de Leeuw
200284764
magnet (Sodium). Thus, Chlorine will pull it’s electrons in close reducing its size. You
can also talk about trends in electro negativity here.
 The trend to be extrapolated is that going left to right across the rows will decrease
atomic size. It is also important to note that going down the table will increase in size
because the new orbitals added are farther away from the nucleus as a whole.
Those are the three trends I observed while I was in the field, and I thought up this idea while
watching. In all cases, you could use students, magnets, or different sized balls to illustrate your
point. You could even use something like Jenga if you found a use for it. These are simply
simulations, so don’t let my ideas stifle your creativity.
Again, this can easily be followed up by an exit slip. If you wanted to push understanding more,
you could also ask them to come up with their own simulation to explain these occurrences.