Inorganic question regarding Phosphorus-32 [closed]








**Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers.
 
 






---








 **Homework questions** must demonstrate some effort to understand the underlying concepts. For help asking a good homework question, see: [How do I ask homework questions on Chemistry Stack Exchange?](https://chemistry.meta.stackexchange.com/questions/141/how-do-i-ask-homework-questions-on-chemistry-stack-exchange)




Closed 1 year ago.








[Improve this question](/posts/161678/edit) 



[![enter image description here](https://i.stack.imgur.com/2hRDV.png)](https://i.stack.imgur.com/2hRDV.png)


I am learning Inorganic Chemistry recently, and doing some pass year paper, and found this question. i am not sure how to identify A3+.
Pls Help for question 1 ,2 ,& 3




Isoelectronic means it has the same electronic structure and number of electrons, for example a negatively charged hydrogen ion (hydride) is isoelectronic with a helium atom.


Now phosphorus forms a simple 3- ion which appears in solids such as aluminium phosphide, the phosphide anion is isoelectronic with an argon atom. If we count three atomic numbers forwards from argon we go


Argon, Potassium, Calcium, Scandium. So A is scandium. If we remove three electrons from a scandium atom then we end up with a trication which is isoelectronic with argon.


 1