Apiston in a heat engine does 600 joules of work and 1,700 joules of heat are added to the system. determine the change in internal energy and explain how this example demonstrates the conservation of energy.

The change in internal energy is calculated by obtaining the difference between the heat and the work. That is,
                       change in internal energy = 1,700 J - 600 J
                                                                       = 1,100 J
This is an example of conservation of energy because the energy that is not used for the worked performed is converted to internal energy. 

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.