In Mendeleev's 1871 periodic desk, copper, silver, and gold are outlined two times, after beneath group VIII (with the iron triad and platinum group metals), and at the time underneath group IB. Group IB was nonetheless parenthesised to notice that it was tentative. Mendeleev's main criterion for group assignment was https://bigbos777-link82457.full-design.com/bigbos777-daftar-things-to-know-before-you-buy-78190247