Why spdf stands in the periodic table?

Answer 1

s,p,d and f are designations for the four different types of subshells.

s is spherical in shape and has only one orientation in three dimensional space.

p has a dumbbell shape and has three orientations:

Px, Py and Pz.

d has a double dumbbell shape and has 5 orientations. Dxy, Dyz, Dxz, Dx2-y2, Dz2

f has a complex shape and has 7 orientations.

Each orbital can hold 2 electrons. s having only 1 orientation can hold only 2 electrons. p having 3 orientations, has 3 orbitals, each having the capacity to hold 2 electrons, so it can totally hold (3X2=) 6 electrons.

Similarly d can hold (5X2=) 10 electrons and f can hold (7X2=) 14 electrons.

The letters s, p, d, f respectively stand for sharp, principal, diffused and fundamental.

In the Periodic Table depending on which sub-shell is the valence shell (outermost) we have the spdf blocks.

The s-block is the alkali metals and alkaline earth metals.

The p-block is the non-metals and metalloids.

The d-block has the transition metals.

The f-block has lanthanides and actinides(mostly radioactive).