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: H2 )

Covalent Compounds• Use prefixes to tell how many atoms of

an element are in a formula.

• Prefixes:p. 533 chart

• CO2 This is carbon dioxide. There is no prefix on carbon b/c there is only one and it’s the first element.

• N2O 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