Periodic Table Blocks Explained: s, p, d, and f Blocks
The periodic table is split into four blocks — the s-block, p-block, d-block, and f-block. Each block is named for the subshell that holds an element's highest-energy (valence) electrons. An element's block tells you a lot about how it behaves, and you can find it just from the element's position or its electron configuration. Here's how the four blocks work.
The s-block
The alkali metals and alkaline earth metals — the reactive metals on the far left — plus hydrogen and helium. Its valence electrons fill the s subshell (up to 2 electrons).
The p-block
Most nonmetals, all the metalloids, and the metals on the right side of the table. Its valence electrons fill the p subshell (up to 6 electrons).
The d-block
The transition metals in the middle block of the table. Its valence electrons fill the d subshell (up to 10 electrons).
The f-block
The two rows shown beneath the main table. Its valence electrons fill the f subshell (up to 14 electrons).
How to find any element's block
Write out the element's electron configuration and look at the last subshell that gets filled. Aluminium is [Ne] 3s² 3p¹ — it ends in a p subshell, so aluminium is in the p-block. You can also just read it off the table: groups 1–2 are the s-block, groups 13–18 the p-block, groups 3–12 the d-block, and the two rows below are the f-block.
Frequently asked questions
What are the four blocks of the periodic table?
The periodic table is divided into the s-block, p-block, d-block, and f-block. Each block is named for the type of subshell (s, p, d, or f) that holds the element's highest-energy, or valence, electrons.
What block is aluminium in?
Aluminium is in the p-block (group 13, period 3). Its electron configuration, [Ne] 3s² 3p¹, ends in a p subshell, which places it in the p-block.
How do you know which block an element is in?
Look at where the element's last (highest-energy) electron goes. If it fills an s subshell the element is in the s-block, a p subshell the p-block, a d subshell the d-block, and an f subshell the f-block. You can also read it straight off the table by the element's column position.
Why are they called the s, p, d, and f blocks?
The letters come from old spectroscopy terms used to describe spectral lines: sharp, principal, diffuse, and fundamental. Those names were later attached to the electron subshells, and the blocks take their names from the subshells they fill.
See the blocks in action
Explore all 118 elements and check the block of any one of them.