Final answer:
Oxygen (O) is the nonmetal that has atoms with 6 valence electrons, which is 2 more than Silicon's 4 valence electrons, making it the element with 2 more valence electrons than Silicon.
Step-by-step explanation:
The element that is a nonmetal with atoms having 2 more valence electrons than Silicon (Si) is Oxygen (O). Silicon (Si) is in group 14 of the periodic table and has 4 valence electrons. As nonmetals tend to gain electrons to complete their octet, Silicon would need 4 more electrons to complete its octet
An element with 2 more valence electrons than Silicon would thus need 6 valence electrons, as it would need 2 additional electrons to complete the octet. Oxygen, which is in group 16 of the periodic table, meets this criterion as it has 6 valence electrons and needs 2 more to complete its octet. Hence, the correct answer is D. Oxygen (O).