The first hour bell rings stimulus or response?

The ringing of the bell was Introduced as a neutral 

stimulus by Pavlov. A stimulus which leads to an 

automatic response is an unconditioned stimulus. 

The food was the unconditioned trigger in Pavlov's 

experment. An automatic response to a stimulus is an  unconditioned response.

ionic bonds are two oppositely charged ions that attract. a sodium ion has a 1 positive charge; a chloride ion has a 1 negative charge. sodium and chloride have oppostive charged ions that attract which forms an ionic bond. a chemical bond formed when two atoms share electrons is called