0am:The Winthrop, MA forecast for Mar 16 is 23 degrees and Clear. There is 70 percentage chance of rain and 21 mph winds from the West. 3am:The Winthrop, MA forecast for Mar 16 is 22 degrees and Clear. There is 73 percentage chance of rain and 19 mph winds from the West-Southwest.
Noun. 1. reactant-a chemical substance that is present at the start of a chemical reaction. chemical, chemical substance-material produced by or used in a reaction involving changes in atoms or molecules.1  Facebook.eactant. n. 1. (Chemistry) a substance that participates in a chemical reaction, esp a substance that is present at the start of the reaction. Compare product 4. (riËaek riËÃ¦k). tÉnt
Expert on ancient and European history. A chemical reaction occurs when one or more chemicals react to become different chemicals. A chemical reaction is characterized by the re-arrangement of atoms from the reactant side of the equation to the product side.It's a bit like square dancing because at any given time you may have a different partner than when you started but no matter how you re-arrange the dancers, you always have the same people. chemical reaction is a change in which one kind of matter changes into a different kind of matter with different properties. Reactant is a substance used in a chemical react â¦ ion and a product is a substance made in a chemical reaction. Hope this is helpful! ;).