Pure element
Pure elements (anisotopic element) exist on earth only in the form of a single stable or long-lived isotope. Their atoms have the same atomic mass and agree in all other properties.
9F
Fluorinevery pale yellow (gas); bright yellow (liquid); alpha is opaque, beta is transparent (solid)
15P
Phosphoruswhite, red and violet are waxy, black is metallic-looking
59Pr
Praseodymiumgrayish white