When a 8 gram slice of bread is burned under a beaker of 4500 grams of water, it heats up the water by 1.3 degrees Celsius. The specific heat of water is 1 cal/g degree C. How many calories does this slice of bread contain?

I'm learning about the periodic tables and what each subject's configuration is. for example, hydrogen is 1s^1, but i don't understand how you get that. can someone me understand how to figure out how to figure this out? sorry if the question makes no sense, but it would really a lot if you could me understand! you so much if you can!