Here Is a Periodic Tables with the 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 p-orbitals 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.