There are two possible options here:
Iron and oxygen
Potassium has the largest atomic radius. It is in the 1st group of the periodic table. Fluorine has the least atomic radius.
they are two completely different elements
Calcium and fluorine
Calcium and fluorine
Calcium and fluorine
There are metals and non metals in the first 20 elements. Also there are elements of Solid and gas states. These names are, Hydrogen,Helium,Lithium,Beryllium,Boron,Carbon,Nitrogen,Oxygen,Fluorine,Neon,Sodium.Magnesium,Aluminium,Silicon,Sulfur,Chlorine,Argon,Potassium,Calcium.
Every element is different. The atomic number of potassium is 19 and calcium's is 20. Potassium's atomic mass is 39.098 and calcium is 40.08. these two elements are very different. Potassium being an Alkaline Metal while calcium is an Alkaline Earth Metal. You might be thinking. Oh my goodness those are like the same thing, but actually they are very different. Potassium just happens to less dense than calcium.
Helium
Fluorine, electronegativity increases up and to the right on a periodic table of elements.
Hydrogen, Helium, Lithium, Beryllium, Boron, Carbon, Nitrogen, Oxygen, Fluorine, Neon, Sodium, Magnesium, Aluminum, Silicon, Phosphorus, Sulfur, Chlorine, Argon, Potassium, and Calcium.
the 3 elements found in calcium sulfate are calcium,sulfur and oxygen
No. Since potassium is an element by itself, it does not have calcium in them. However, it could combine together to create potassium calcium (which is a vitamin). There are such things as a potassium calcium channel in a cell.