Periodic trends have patterns that exist in the periodic table to illustrate different aspects of elements, including the size and electronic characteristics of elements. Trends include:
ionization energy
The ionization energy of an element usually increases from left to right. This is due to the stability of the valence shell.
The ionization energy of the elements decreases from top to bottom. This is due to electronic shielding.
electronegativity
From left to right in the periodic table, the electronegativity increases.
If the valence shell of an atom is less than half, the energy required to lose electrons is less than the energy required to obtain electrons; it is easier to pull the electron into the valence shell than to donate the electron.
atomic radius
The atomic radius decreases from left to right. This is due to the increase in the number of protons and electrons across a period.
The role of protons is greater than electrons. As a result, electrons are pulled toward the nucleus, resulting in a smaller radius.
The atomic radius increases from top to bottom. This is caused by electronic shielding.
melting point
Metals have a high melting point.
Most nonmetals have low melting points.
chemical reactivity
Period - reactivity increases as you go from the left to the right across a period.
Group - reactivity decreases as you go down the group.
ion charge
On the Periodic Table metals (found on the left of the table) will be positive. Non-metals (found on the right) will be negative.
The alkali metals form +1 ions. Hydrogen can form either +1 or -1 ions. The alkaline earth metals form +2 ions. In group 15, Nitrogen and Phosphorus usually form -3 ions. The halogens always form -1 ions. The noble gases don’t easily form ions. And many of the transition metals form more than one type of ion.
Conductivity
Period - Decreases from left to right
Group - Increases from top to bottom
In order for this element to conduct electricity, it must contain freely moving electrons. Generally, metals are good electrical conductors, and nonmetals are bad electrical conductors.