Periodic Table of Elements

What is this?

A table organizing all 118 known chemical elements by atomic number, electron configuration, and recurring chemical properties. Elements in the same column share similar behaviors.

Why does it matter?

Every material, medicine, and manufactured product is made of elements on this table. Chemists use it to predict reactions, engineers to select materials, and doctors to understand drugs.

Key terms

Element — a pure substance that cannot be broken down further by chemistry Atomic number — the number of protons in an atom's nucleus; uniquely defines the element Period — a horizontal row; elements share the same number of electron shells Group — a vertical column; elements share similar chemical properties Isotope — atoms of the same element with different numbers of neutrons Noble gas — stable, non-reactive gases in Group 18 (Helium, Neon, Argon…)

🎯 Try this challenge

Find the three most common elements in the human body. Search for Oxygen, Carbon, and Hydrogen in the table. Which one has the highest atomic number?

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