Which of the following is not a transition metal? Rhodium, gold, zirconium, potassium, or cobalt.
The best way to answer this question is to refer to our periodic table. Our periodic table is arranged in various blocks. On the far left, we have the s block. On the right, we have the p block. Right in the middle, we have the d block. And these are the elements which we usually refer to as transition metals. We also have this funny extra block right at the bottom that kind of fits into the d block and can sometimes be referred to as inner transition metals. But usually they’re referred to as the actinides and lanthanides.
But the bit we’re interested in for this question is the d block in the middle, the transition metals. What we need to do now is find each of the metals that we’re given in the question and see whether they’re in the d block or not. First, let’s remind ourselves of the symbols that we use to represent each of these metals. Rhodium is Rh. Gold is Au. Zirconium is Zr. Potassium is K. And cobalt is Co.
So now let’s place each of these roughly where it exists on the periodic table. Rhodium is roughly in the middle of the d block in group nine. This makes it a transition metal and means it is not the correct answer to our question. Gold is also in the d block but is towards the right in group 11. This means it too is a transition metal and is not the correct answer. Zirconium is towards the left of the d block in group four and is in the same period as rhodium. This means it is also a transition metal and therefore not the correct answer. Potassium is on the far left of the periodic table in the s block in group one. As you may know, this group is called the alkali metals.
So while potassium is a metal, it’s not a transition metal. So this is a correct answer to our question. Just to be safe, let’s check the last possible answer as well, cobalt. Cobalt is directly above rhodium, also in the d block in group nine. So cobalt is also a transition metal. So, of the five elements given, the only one that is not a transition metal is potassium.