Periodic Trends by Sydney

This week, we have been learning about periodic trends. Before we can get into some of the trends, we have to understand the periodic table and how it is organized first.

The periodic table is a set of elements organized into periods and groups. The elements are also organized by atomic number, usually in rows, so that elements that have a similar structure appear in vertical columns.

Now that we have that down, let’s get into the trends.

In the diagram below, we can see the four main trends.

The first trend is Atomic Radius. Atomic Radius is like a measurement of the atom, showing how far the electrons are from the nucleus.

As you go left and down on the table, the atomic radius increases. This is because the number of electrons increase and more orbitals must be filled, therefore the distance from the nucleus is greater.

The second trend is Electronegativity. Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons.

As you go farther right and up on the table, the electronegativity increases. This is because the positively charged protons in the nucleus attract the negatively charged electrons. Therefore, the electronegativity or attraction increases in the element.

The third trend is Ionization Energy. Ionization energy is the amount of energy it takes to move an electron from a gaseous atom or ion.

As you go farther right and up on the table, the ionization energy increases. This is because the electrons are held tightly in the lowest orbitals, making it harder to move them around.

We see periodic trends because every element is different. There are placed where they are on the periodic table for a reason. Knowing the trends can help us identify differences in elements and make it  easier to understand their unique behaviors. When working with elements, it’s important to know every detail about them. The periodic trends help us understand the elements and the exceptions in the table.

These trends are interesting because not all the elements follow. For example, with electronegativity, the noble gases aren’t included in the trend. They have a full valence shell and usually don’t attract electrons so they do not have an electronegativity measurement. Francium actually has the greatest atomic radius. Another interesting fact is that Helium has the highest ionization energy out of all the elements.

What exceptions can you find in the table?