Chemical element

A chemical element is a pure substance that contains only one type of atom. Each element is different because of its atomic number, which tells how many protons are in its nucleus. There are more than 100 known elements, and they are the basic building blocks of all matter. Everything around us — air, water, rocks, plants, and even our bodies — is made of elements combined in different ways.

Elements are arranged in a chart called the periodic table of elements. This table organizes them based on their properties, such as atomic number, mass, and chemical behavior. For example, hydrogen has one proton and is the lightest element, while uranium has 92 protons and is much heavier. Some elements, like oxygen and carbon, are essential for life, while others, such as gold or iron, are used in tools, coins, and machines.

Each element has a unique chemical symbol, usually one or two letters. For example, oxygen is written as O, carbon as C, and sodium as Na. These symbols are used in chemical formulas to show how elements combine to form compounds. For example, water (H₂O) is made of two hydrogen atoms and one oxygen atom. Salt (NaCl) is made of sodium and chlorine.

Elements can exist in different states of matter, such as solids, liquids, or gases, depending on temperature and pressure. Metals like iron and copper are solids at room temperature, mercury is a liquid metal, and gases like helium and nitrogen fill the air around us. Some elements are very reactive, like sodium, while others are stable, like noble gases such as argon.

Scientists study elements to understand how substances behave and interact. Discoveries of new elements help expand the periodic table and improve technology, medicine, and materials. The study of elements and their properties is part of chemistry, one of the main branches of science.

In summary, chemical elements are the simplest forms of matter that cannot be broken down by normal chemical means. They combine in countless ways to make all the materials and living things in the universe.