元素同元素之間既結合有無法則之類既野??
即係例如二氧化碳 + 水 (氫+氧)  —) 碳酸
係咪呢一條方程
只會產生出呢個野呢?

又或者 氧化鐵 即係表示鐵只會同空氣中既氧進行化學反應
而二氧化碳 氬 氮個d就 唔會 / 唔會咁易同鐵做到化學反應?

當然有法則
化學有部分就是研究以及找出這些法則

咁ionic,covalent算唔算係法則?

No, those are only the descriptions of existing chemical interactions between elements, not the rules that guide the formation of susbtances from elements.

ha, 好可惜, 唔係完全有法則
例如一個反應會放氧:
AO2+B ->AB+O2
點解唔係咁?
3AO2+3B -> 3AB+2O3
呢個問題唔會有人知...我個老師咁講

In fact one can figure out why O2 is formed instead of O3 in your example through theoretical modeling. Of course, the reasons will be on case-by-case basis, and may not be easily generalized for all possible cases.