Ya if you can show us an example of the valency thingy then that would help
Thanks
eg- 2,8,8,2 so 2 is the outer electron and it needs 6 more to become stable
now they'll give you another element 2,6 to make it stable.
The nos. may vary so you can take 3 or 2 structures of an element and this will help to deduce formula !!
Same for covalent bonding
+rep if it helped !!