What factor determines that an oxygen atom can form two covalent bonds while a carbon atom can form four?

This is to do with the number of electrons in its outer electron shell. This is what determines how reactive it is and how many bonds can form because once the outer shell is full and hits the limit of eight, no more bonds can be formed.

Find out more about Biology

Related Questions:

What Can Happen To An Ear Canal If Damaged?
What Is The Process Of Meiosis?
What Are Somes Uses For Proteins
What Is Photosynthesis?
What's The Difference Between A Plant Cell And An Animal Cell?