Which sub atomic particle always determines the elemental identity of an atom

Which best describes why nh4+ can form an ionic bond with cl-?

The skeletal system performs a variety of functions that are crucial to maintaining life processes. what function is performed in the bone marrow, but not in the ossified bones of the skeleton? a oxygen transportation c mineral storage b. muscle attachment d red blood cell production

In which of these cases are the two wave points considered to be in phase with each other?