What makes an atom able to form a compound? * O different number of neutron than protons O unfilled outer electron shells O same number of protons as electrons O a positive ot negative charge of the nucleus

same number of protons as electrons

Explanation:

The addition of a neutron can make an atom radioactive. When you change the number of protons in an atom, you will change the atom from one element to a different element. ... If you change the number of electrons in an atom, you will get an ion of the element.