When milk goes sour, what type of change has happened?
a. physical only
b. chemical only
c. physical and chemical

C! Sometimes, when you pour your milk, it may come out as a cottage-cheese like texture and it may smell really bad. Also, When the amount of lactic acid in the milk begins to increase, the pH drops and the casein molecules begin to clump. The high levels of lactic acid are also what give spoiled milk its characteristically sour smell. Hope this helped!

It won't lose or gain electrons if it's a covalent bond it shares the electrons with another atom or atoms. if it is an ionic bond it will lose the 3 electrons on the outer shell and become a positively charged ion.  credit goes to @sunshinebaby of answers.yahoo.com.