1. Atom: The basic unit of a chemical element, consisting of a nucleus containing protons and neutrons, surrounded by electrons.
- Example: An atom of oxygen typically contains eight protons.
2. Molecule: A group of atoms bonded together, representing the smallest fundamental unit of a chemical compound.
- Example: Water is composed of two hydrogen atoms and one oxygen atom bonded together to form a molecule.
3. Compound: A substance formed when two or more chemical elements are chemically bonded together.
- Example: Carbon dioxide is a compound composed of carbon and oxygen atoms.
4. Chemical Reaction: The process in which one or more substances (reactants) are converted into different substances (products) by the rearrangement of atoms.
- Example: Combustion is a chemical reaction that produces heat and light.
5. Acid: A substance that donates a proton or accepts an electron pair in reactions and turns litmus red.
- Example: Lemon juice contains citric acid, giving it its sour taste.
6. Base: A substance that can accept protons or donate electron pairs in reactions, turning litmus blue.
- Example: Sodium hydroxide is a strong base commonly used in cleaning products.
7. pH: A scale used to specify the acidity or basicity of a solution, with a range from 0 to 14, where 7 is neutral, values below 7 are acidic, and values above 7 are basic.
- Example: The pH of stomach acid is typically around 1.5 to 3.5.
8. Catalyst: A substance that increases the rate of a chemical reaction without being consumed in the process.
- Example: Enzymes are biological catalysts that speed up chemical reactions in living organisms.
9. Bond: A chemical link between atoms that holds them together in a molecule.
- Example: The covalent bond in hydrogen molecules consists of shared electrons.
10. Oxidation: A chemical reaction in which a substance loses electrons, often resulting in the addition of oxygen or the loss of hydrogen.
- Example: Rusting of iron is an oxidation reaction where iron reacts with oxygen to form iron oxide.
