Vocabulary 3: Chemical Changes

1 Compound: A chemical combination of two or more elements.  



2 Chemical Bond: a link that atoms or electrically charged particles can form with each other. 



3 Chemical Formula: a way of using letters and numbers to show how much of each element is in a substance.  



 4 Ion: an electrically charged particle with unequal numbers of protons and electrons.  



5 Molecule: a group of bonded atoms that acts like a single.  



6 Chemical Property: a way of describing how a substance changes chemically with other substances.

  
7 Exothermic: a reaction that gives off heat.



8 Endothermic: a reaction that absorbs heat.