I NEED HELP PLEASE! :)

Describe the energy change when an electron moves from one energy level in an atom to another, both to a higher energy state and to a lower energy state. Tell whether a photon is absorbed or released in each case.

How do you know when a chemical reaction has occurred

Which change will decrease the number of effective collisions during a chemical reaction? a. adding a catalyst b. increasing the surface area c. decreasing the temperature d. increasing the reactant concentrations e. increasing the volume of the reactants

What is the difference between covalent bonds and ionic bonds? covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the electrical attraction between charged atoms. covalent bonds involve the transfer of electrons between charged atoms; ionic bonds involve the sharing of electrons between atoms. covalent bonds involve the sharing of pairs of electrons between atoms; ionic bonds involve the sharing of single electrons between atoms. covalent bonds involve the sharing of electrons between atoms; ionic bonds involve the sharing of protons between charged atoms.