Question

if a -2 ion has 34 protons, what element is it?
germanium (ge)
selenium (se)
krypton (kr)
chlorine (cl)

Explanation:

The atomic number of an element is equal to the number of protons in its nucleus. The element with atomic number 34 is selenium (Se). The -2 ion indicates that it has gained 2 electrons, but the number of protons (which defines the element) remains 34. Germanium (Ge) has atomic number 32, krypton (Kr) has atomic number 36, and chlorine (Cl) has atomic number 17.

Answer:

selenium (Se)