Chemical Reaction Clues Gas formation: bubbles may indicate a chem. Reaction Solid formation: a solid forms in a liquid (a precipitate) Color change: example-bleach reacts w/ fabric dye making it change Energy change: heat or energy being released or absorbed. These are only clues that a reaction MIGHT be taking place!

Formulas Shorthand notation for a compound or molecule Subscripts are written below and to the right of the symbol (Ex: H 2 )

Covalent Compounds Use prefixes to tell how many atoms of an element are in a formula. Prefixes:p. 533 chart CO 2 This is carbon dioxide. There is no prefix on carbon b/c there is only one and it’s the first element. N 2 O Dinitrogen monoxide Di- means there are two nitrogen ; mono means there is one oxygen

Ionic Compounds No prefixes are used; however, the suffix – ide is added Example: NaCl is sodium chloride (change chlorine to chloride) The charges must equal out; so, Na has a charge of +1; Cl is –1; +1-1=0