A periodic trend is a tendency in the properties in elements on the periodic table.
Trends may have exceptions however.
-
Elements in the same period have the same number of occupied electron shells.
-
Elements in the same group have similar reactivity.
-
Atomic radius increases left and down.
-
First ionisation energy increases up and right. Going up the eletrons are closer to the nucleus so hard to remove, going right there is more core charge so hard to remove.
-
Metallic character increases down and left.
-
Reactivity increases down for metals and increases up for non-metals.
-
Electronegativity increases up and right, except for group 18.