Question

the number of protons an element has is its ___, whereas the number of electrons will determine ___.
mass number; atomic number
atomic number; atomic mass
atomic mass; the type of bond it can form
atomic number; the type of bond it can form
atomic mass; atomic number

Explanation:

The number of protons in an element is defined as its atomic number, which uniquely identifies the element. The number of electrons (specifically valence electrons) determines an atom's reactivity and the type of chemical bond it can form (e.g., ionic, covalent).

Answer:

atomic number; the type of bond it can form