Similar to strong acids, strong bases will also completely ionize, or dissociate, in solution. Strong bases will dissociate 100 percent of hydroxide ions (OH-) in water.

For example, lithium hydroxide will completely dissociate into lithium ions and hydroxide ions when placed in water.

Watch this animation and classify NaOH and NH₃ as strong or weak acids.

1. Which is the stronger base, NaOH or NH₃ ?

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   Check Your Answer
   NaOH is the stronger base.

2. To what degree does NaOH ionize (break apart)?

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   Check Your Answer
   NaOH breaks apart completely (100 percent).

3. To what degree does NH₃ ionize (break apart)?

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   Check Your Answer
   NH₃ breaks apart to a limited extent (very little).

4. What happens to the amount of NaOH in solution as the amount of Na⁺ and OH^- increases?

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   Check Your Answer
   As the amount of Na⁺ and OH^- increases, the NaOH in solution decreases.

All of the bases formed from Group 1 and Group 2 metals, with the exception of beryllium, are strong bases. Listed below are nine bases that fit the definition of a strong base. All other bases are considered weak. For example, ammonia (NH₃) is considered a weak base because it does not dissociate OH- ions.