Chemistry Vocabulary

2. A substance that speeds up a chemical reaction by lowering the activation energy without being consumed in the process.
4. A symbolic representation of a chemical reaction, showing the reactants and products with their quantities.
7. The solid part of Earth, including rocks, soil, and fossil fuels.
8. A weak bond formed between the slightly positive hydrogen atom of one molecule and the slightly negative atom (like oxygen) of another molecule.
9. A principle stating that energy cannot be created or destroyed; it can only be transferred or transformed.
14. The part of Earth where life exists, including all living organisms.
15. A process in which reactants are transformed into products by breaking and forming chemical bonds.
16. A chemical reaction that absorbs energy, often resulting in a cooling effect. Example Photosynthesis.
17. The layer of gases surrounding Earth, including nitrogen, oxygen, and carbon dioxide.
19. The starting substances in a chemical reaction that undergo a change to form products.

1. The minimum energy required to start a chemical reaction.
3. The movement of carbon through Earth’s four spheres (atmosphere, biosphere, hydrosphere, geosphere) via processes like photosynthesis, respiration, and combustion.
5. A chemical reaction that releases energy, usually as heat or light. Example Combustion.
6. A principle stating that mass cannot be created or destroyed in a chemical reaction; the mass of the reactants equals the mass of the products.
10. A force that holds atoms together in a molecule. Types include covalent, ionic, metallic, and hydrogen bonds.
11. All of Earth’s water, including oceans, lakes, rivers, and groundwater.
12. A molecule with an uneven distribution of charge, creating a positive side and a negative side. Water is a polar molecule.
13. A group of two or more atoms chemically bonded together. Molecules can consist of the same type of atom (e.g., O₂) or different types (e.g., H₂O).
17. The smallest unit of an element that retains its chemical properties. Atoms consist of a nucleus made of protons and neutrons, surrounded by electrons.
18. The substances formed as a result of a chemical reaction.