Introduction to Periodic Trends The Periodic Table of Elements is not just a list of elements—it's a powerful tool that helps us understand how elements behave based on their position. One of the most important features of the periodic table is the presence of periodic trends . Periodic trends are patterns in the properties of elements that repeat at regular intervals (or “periods”) across the table. These trends help scientists predict how elements will react, bond, and interact with other substances. Major Periodic Trends Atomic Radius Definition : The distance from the nucleus to the outermost electron. Trend : Decreases across a period (left to right) Increases down a group (top to bottom) Ionization Energy Definition : The energy required to remove an electron from an atom. Trend : Increases across a period Decreases down a group Electronegativity Definition : An atom's ability to attract electrons in a chemical bond. ...