Often after an acute injury of the knee the quadriceps muscle will not contract, which is called âquad inhibition.â. Inability to straighten the leg. Athletes with acute patellar injuries may find that they cannot flex the knee joint fully or straighten the leg. This may be exacerbated by swelling of the knee.
The alkali metals are a group (column) in the periodic table consisting of the chemical elements lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr).
A. Alkali metals exist in pure form; alkaline earth metals appear in nature as compounds. B. Alkali metals are much harder than the alkaline earth metals. C. Alkali metals are much less reactive than alkaline earth metals. D. Alkali metals have one valence electron and alkaline earth metals have two.