Introduction to chemistry
What is Chemistry?
Chemistry is the branch of science that studies matter — its composition, structure, properties, and the changes it undergoes. In simple terms, chemistry helps us understand what things are made of and how they interact with each other.
Ideas in Chemistry
- Matter
Anything that has mass and occupies space (e.g., air, water, metals).
- Atoms and Molecules
Atom: the smallest unit of an element that still retains its properties.
Molecule: two or more atoms bonded together (e.g., H₂O).
- Elements and Compounds
Element: pure substance made of only one type of atom (e.g., oxygen, gold).
Compound: substance made when two or more elements combine chemically (e.g., water = hydrogen + oxygen).
- Mixtures
A combination of substances not chemically bonded (e.g., saltwater, air).
- Chemical Reactions
Processes where substances (reactants) change into new substances (products).
Example: 2H₂ + O₂ → 2H₂O
- Branches of Chemistry
Physical Chemistry – studies energy and matter.
Organic Chemistry – studies carbon compounds.
Inorganic Chemistry – studies compounds without carbon.
Analytical Chemistry – focuses on composition of substances.
Importance of Chemistry
Explains everyday processes (cooking, cleaning, breathing).
Used in medicine, agriculture, industry, and technology.
Helps solve global problems like pollution, energy shortage.