How our body/soul is composition of five elements?
According to Theravada Buddhism a person (satva) is explained in terms of six major elements. Patavi,Apo,Tejo,vayo,Akasa (space) and vinnana (consciousness)
The way I understand these elements are smaller than atoms. They are even not physical. The Buddhist term for them is Dathu.

https://www.accesstoinsight.org/tipitaka/mn/mn.140.than.html