Why is -LSB- math -RSB- \ mathrm -LCB- Cr -RCB- ^ -LCB- 6 + -RCB- -LSB- / math -RSB- -LRB- hexavalent chromium -RRB- more toxic than -LSB- math -RSB- \ mathrm -LCB- Cr -RCB- ^ -LCB- 3 + -RCB- -LSB- / math -RSB- -LRB- trivalent chromium -RRB- ?
Why is the size of chromium greater than vanadium ?