P-block

The p-block is a section of the periodic table of chemical elements. It consists of elements whose outermost electron—the highest-energy electron being filled—enters a p orbital. The p orbital can hold up to six electrons, which means the p-block contains six columns.

The p-block elements begin at group 13 and end at group 18 in the modern periodic table. It contains metals, metalloids, and non-metals, as well as the inert gases. The p-block shows greater variation in chemical properties than any other block.

Electron configuration

The general electron configuration of p-block elements is ns² np¹⁻⁶, where n is the period number. For example, oxygen in period 2 has the configuration 1s² 2s² 2p⁴. When the p orbital is completely filled (np⁶), the element achieves high stability—which is why the noble gases in group 18 are unreactive. Helium is in group 18, but its configuration is 1s², so it is usually classified as belonging to the s-block.

Groups in the p-block

The p-block groups are: group 13 (boron and aluminium), group 14 (carbon and silicon), group 15 (nitrogen and phosphorus), group 16 (oxygen and sulfur), group 17 (halogens such as fluorine and chlorine), and group 18 (noble gases such as neon and argon). The elements essential to life—carbon, nitrogen, oxygen, and phosphorus—all belong to this block.

Variation of properties

Moving from left to right across a period, ionization energy and electronegativity increase, while atomic radius decreases. Moving down a group, metallic character increases: for example, group 14 begins with carbon, a non-metal, and ends with tin and lead, which are metals. The metalloid boundary—marked by boron, silicon, germanium, arsenic, antimony, and tellurium—lies between these two categories.