Carbon dioxide contains bonds between oxygen and carbon. what particles are between the carbon and oxygen atoms ? what keeps those particles between the atoms ?

There are electrons between the carbon and oxygen atoms.

The electrons have a negative charge. The nuclei of the atoms are positively charged.

The electrical attraction between oppositely charged particles keeps the electrons between the atoms.

the potential energy of the reactants is 200j.

from the energy diagram, the energy of the product formed is 350j; this means that, this reaction is an endothermic reaction, because it absorbs energy from its environment.