Question

Which of the following group of elements are generally colorless?

• A. $3$ to $12$ i.e. transition elements
• B. $1,2,\&13$ to $17$ i.e. normal elements
• C. $3$ to $12$ i.e. normal elements
• D. $1,2,\&13$ to $17$ i.e. transition elements

Answer 1

The correct option is B $1,2,\&13$ to $17$ i.e. normal elements

The colors come from interactions of the ion electrons with light. All ions interact to some extent [except H+, since it has no electrons with which to interact], but the D block elements interact in the visible light. The reason for this has to do with the fact that electrons can only exist at certain energy levels, and the electron energies specific to the D block. The difference in energy between electron levels correspond to a specific color of light, and the D block elements have energies that correspond to colors you can see. S and P block elements don't have the same energies, don't interact with light that you can see, and so appear colorless.