Download Periodic Trends

Periodic Trends Lab
The Periodic Table is arranged by atomic number and the resulting patterns
of electron configurations, element properties, bond type, and what we call
the periodic trends. The trends include atomic radii, ionic radii, ionization
energy, and electronegativity.
Atomic radii (AR) are the size of the atom, which is ½ the distance of the
atoms bonded together. Ionic radii (IR) deal with the size of the ions once the
electrons are lost or gained by the original atom. Electron affinity (EA) is the
energy released when an electron is gained. Ionization energy (IE) is the
amount of energy required to remove 1 electron from an atom. There is 1st
ionization energy, 2nd ionization energy etc. Electronegativity (EN) is used in
bonding by calculating the difference in EN to determine if the bond is ionic,
polar covalent or nonpolar covalent. EN is essentially the pull on the
electrons in the bond of the atoms in the bond.
Here is a Periodic Tables with the trends.
Here is another table from a different perspective. I like this one because it
shows metallic and nonmetallic character. And the diagonal lines are a good
way to view the trends.
Atomic radii is key to
understanding the other
trends. AR increases as
we move from top to
bottom because we are
adding energy levels. By
the way the trends using
only the s-orbitals and porbitals is more evident. So AR
increases as we go down the Periodic Table. That makes sense. AR
increases from the right to the left. This means the upper right hand corner of
the PT has the smaller
atoms. Let’s take Na and Cl
for example. They are both
on n=3. But Cl has 17
protons pulling on n=3 and
Na only has 11 protons
pulling on n=3. Cl is smaller
because it’s nuclear charge
is greater. That fact is very
important for the trends.
Once we can see that the
nonmetals tend to be
smaller with a greater force
holding the electrons, we can see that it takes a lot of energy to remove an
electron as with IE. And the nonmetals will pull harder on electrons in a
bond as in EN. As you can see from this data table above there are
additional reasons for the trends.
What we are doing today is searching online for the AR, IE, and EN values.
Only for the s and p-orbitals. I want you to enter the data in Excel and graph
these values vs the atomic number of the element. Put the atomic numbers on
the x-axis. So keep track of the atomic numbers while you are finding the
values. For EN use the Pauling scale.
You will see the periodic nature of the periodic table and its trends.