Answer the following question given this paragraph: 

A compound is a unique substance that forms when two or more elements combine chemically. Compounds form as a result of chemical reactions. The elements in compounds are held together by chemical bonds. A chemical bond is a force of attraction between atoms or ions that share or transfer valence electrons. For a video introduction to compounds, go to this URL: http://www. youtube. com/watch?v=-HjMoTthEZ0 .


Q: What type of reactions form compounds?


A:
chemical reactions