True or false? The maximum covalency in 2nd
period elements is 4
. Why is this true if fluorine can only make one bond?

False. While the statement that the maximum covalency in 2nd-period elements is 4 is generally true, there's a slight misunderstanding here. Fluorine indeed forms only one covalent bond in most of its compounds. However, when we speak of the maximum covalency, we consider the highest number of covalent bonds that an atom of an element can form under certain conditions.

In the case of fluorine, even though it typically forms only one covalent bond, its maximum covalency is still 4. This is because fluorine has 7 valence electrons, and it can accept up to 3 additional electrons to complete its octet, making a total of 4 bonds. This is observed in compounds like SF4 (sulfur tetrafluoride), where sulfur forms 4 covalent bonds, three with fluorine atoms and one with a lone pair of electrons.

So, while fluorine usually forms only one bond, its maximum covalency allows for the formation of up to 4 bonds in certain compounds.