This idea is in my mind for some weeks. The principle is simple: An element from PSE should be find out by clues and informations about them. The member who thought an element out give a clue first, then other members ask questions about the element (the position in PSE and the properties), then the member who thought the element out give answers to the questions in the form of 'yes' and 'no'. If a member believes to know the element, then the member names it. If the answer is right, then the member who have guessed the element is the next to think a new element out, if the answer is wrong, then it goes on. Ready? here we go!
What is the element? here is a clue!
The element which is in my mind counts to the halogens, but its not radioactive!