Elements with only a 1s² orbital configuration are the alkali metals in the first column of the periodic table. These include:

* Hydrogen (H)

* Lithium (Li)

* Sodium (Na)

* Potassium (K)

* Rubidium (Rb)

* Cesium (Cs)

* Francium (Fr)

Why?

* 1s orbital: This is the lowest energy level in an atom. It can hold a maximum of two electrons.

* Valence electrons: Alkali metals have only one valence electron, which resides in the 1s orbital.

Let me know if you'd like more details on electron configurations or atomic structure!