- A chemical reaction occurs when atoms separate, come together, or rearrange to form new substances with new properties. Coming together is synthesis, going apart is decomposition.
- A chemical reaction can also release heat and light. Endothermic-heat gained. Exothermic-heat released. The formation of a SOLID also indicates a chemical reaction has taken place. Solid is called a precipitate.
- A chemical reaction can also be seen in rust, tarnishing, and carbonate drinks
- molecule-atoms that combine with other atoms to form larger units
- compound-two or more elements chemically combine to form a new substance totally different from the elements that make up the compound. salt= Na+Cl----> NaCl
- ALL COMPOUNDS ARE MOLECULES BUT ALL MOLECULES AREN'T COMPOUNDS
- C6H12O6=sugar, H2O=water, CO2= oxygen
- Formulas use element symbols with subscripts numbers (ex: H2O=2 elements 3 atoms)
- 6CO2+6H20------>C6H1206+6O2 = PHOTOSYNTHESIS AND OTHER WAY AROUND IS RESPIRATION
- SUPERSCRIPT TELLS HOW MANY MOLECULES THE ELEMENT REQUIRES TO GO THROUGH THAT CHEMICAL REACTION