Answer:
Element is made up of the atoms or isotopes. Isotopes are where only neutrons change in number, such as 3 turning to 2 or to 5. Atom is where it is not changed and it is the original, and example is instead of Carbon13 it is just Carbon. I hope this helps.
There are eight protons in an Oxygen's nucleus.
Answer:
CaCl2
Explanation:
For every calcium there's 2 chlorine
6.4*10^10 is the answer in scientific notation