Germanium is a group 14 element, which means it has four valence electrons. In a monatomic gas, each germanium atom is surrounded by four other germanium atoms, and each atom shares its four valence electrons with the four atoms that surround it. This results in a stable configuration of eight electrons around each germanium atom.

In contrast, many group 16 elements, such as oxygen and sulfur, form diatomic gases in pure form. This is because group 16 elements have six valence electrons, and they need to share two of these electrons with another atom in order to achieve a stable configuration of eight electrons around each atom.