Potassium -- K
Potassium is the third of the alkali metals. Element 19 on the periodic table, its most common isotope has 20 neutrons, giving it a mass number of 39. Like the other alkali metals, it has one unpaired electron in an S shell, in this instance, the electron configuration is [Ar]4s1.
K is considered highly reactive, yet not as reactive as lithium or sodium, two other alkali metals. It reacts violently with water to form a strong base (KOH) and is soft in its pure form.
June 15, 1999
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