Chemistry – The Periodic Table - Arrangement of elements | e-Consult

The periodic table is extremely useful for predicting the properties of elements because it shows a clear relationship between an element's position and its chemical and physical properties. This relationship arises from the recurring patterns in electron configurations.

Properties that can be predicted include:

• Metallic Character: Elements on the left side of the periodic table (metals) tend to be more metallic, meaning they readily lose electrons. As you move across a period, metallic character decreases. Elements on the right side of the table (non-metals) are generally non-metallic.
• Reactivity: Metals in Group 1 (alkali metals) are highly reactive, while metals in Group 2 (alkaline earth metals) are less reactive. Non-metals are generally unreactive.
• Ionization Energy: The ionization energy (the energy required to remove an electron) generally increases across a period and decreases down a group. This is because the effective nuclear charge increases across a period, making it harder to remove an electron.
• Atomic Radius: Atomic radius generally decreases across a period and increases down a group. This is due to increasing effective nuclear charge across a period and increasing shielding by inner electrons down a group.
• Electronegativity: Electronegativity generally increases across a period and decreases down a group. This is related to the ability of an atom to attract electrons in a chemical bond.

The periodic table helps with this prediction by showing the group an element belongs to. For example, knowing an element is in Group 1 tells you it's an alkali metal and therefore likely to be highly reactive and readily lose an electron. Knowing an element is in Period 3 tells you it has 3 electron shells, which influences its chemical properties.