Why would chemical reactions be impossible if electrons did not exist in the outer shells of atoms?
A chemical reaction is simply an electrical reaction between atoms/molecules. the imbalance of an atom seeks to balance through an exchange or regrouping of electrons. Without the electrons, or imbalance thereof, there can be no chemical reaction.
Each element alone has a fixed amount of electrons which may or may not fill their outer shell. If the element has a positive or negative charge due to the proton electron balance, it will combine with another element in order to neutralize its outer shell thus causing a chemical reaction. There exist a few elements that have complete outer shells and thus do not combine with other elements. These are known as inert gases. There are at 4 types of outer shells forming different shapes. The easiest one to comprehend is the s shell which is spherical in shape. The other 3 shells are described as p, d & f shells. The no. of electrons associated with each element is unique to that element and dependent upon the no. of protons in the element. Protons are a positive charge. The nucleus of the element consists of protons and neutrons.
I thought it was because:
The outer shells must be complete to become stable, so if it wasn't complete then it would be unstable. But then if it had no outer shell/any electrons, would there be an atom in the first place?