Chemistry explains how matter is built, how substances change, and why those changes matter in the world around us.
Chemistry is the science of matter and change. It helps us understand what substances are made of, how atoms join together, why reactions happen, and how new materials form. From cooking and medicine to batteries and clean water, chemistry is part of daily life even when we cannot see the atoms and molecules involved.
Atoms are tiny building blocks, and elements are pure substances made from one kind of atom.
Learn MoreAtoms can bond together to form molecules and compounds with new properties.
Learn MoreThe periodic table organizes the elements and reveals patterns in how they behave.
Learn MoreReactions rearrange atoms, turning starting substances into different substances.
Learn MoreAcids and bases have different chemical properties that can be compared using the pH scale.
Learn MoreFood, medicines, cleaning products, fuels, batteries, and materials all depend on chemistry.
Learn MoreAll ordinary matter is made of atoms. An atom has a tiny central nucleus containing protons and neutrons, with electrons occupying regions around it. The number of protons in the nucleus determines which element the atom belongs to. Hydrogen has one proton, carbon has six, oxygen has eight, and every other element has its own proton number. Atoms are extremely small, so chemists usually study huge collections of them at once rather than individual atoms.
Atoms often join through chemical bonds. A molecule forms when two or more atoms are bonded together, while a compound contains atoms from at least two different elements. Water is a familiar compound made from hydrogen and oxygen, yet it behaves very differently from either element by itself. The structure and arrangement of atoms influence a substance's properties, which is why changing how atoms are connected can create entirely different materials.
The periodic table arranges the known chemical elements by atomic number and groups elements with similar behavior into columns. This organization helps scientists predict properties such as how easily an element reacts, what kinds of bonds it tends to form, and whether it behaves like a metal, nonmetal, or something in between. The table is not simply a list; it is a map of repeating chemical patterns that reflects the structure of atoms themselves.
During a chemical reaction, atoms are rearranged into new combinations. The atoms themselves are not normally created or destroyed, which is why balanced chemical equations keep the same number of each kind of atom on both sides. Reactions can release energy, absorb energy, produce gases, form solids, change color, or create other visible effects. Rusting, burning, digestion, photosynthesis, and baking all involve chemical reactions, though they occur at very different speeds.
Acids and bases are categories of substances with characteristic chemical behavior. The pH scale is commonly used to describe how acidic or basic a water-based solution is, with lower values generally more acidic and higher values more basic. Lemon juice is acidic, while some household cleaners are basic. Strong acids and bases can be hazardous, so laboratory experiments involving them require careful handling, protective equipment, and adult or professional supervision.
Chemistry helps explain why bread rises, how soap removes grease, how medicines interact with the body, how batteries store and release energy, and why different materials have different strengths and textures. Chemists also work on challenges such as cleaner fuels, safer medicines, recyclable materials, water treatment, and lower-pollution manufacturing. Understanding chemistry makes it easier to see the hidden processes behind many technologies and products people use every day.