Which element has the lowest electron configuration?

The element with the lowest electron configuration is helium. Helium has the simplest and most stable electron configuration of 1s². This means that it has two electrons, which fill its first energy level completely. As a noble gas, helium is chemically inert and does not readily form compounds, a characteristic of elements with a fully filled electron shell.

In contrast, oxygen, lithium, and boron have more complex configurations. Oxygen has a configuration of 1s² 2s² 2p⁴, which indicates it has six electrons and is more electronegative, actively seeking to gain electrons. Lithium, with a configuration of 1s² 2s¹, has three electrons and is more reactive due to its single electron in the outer shell. Boron has a configuration of 1s² 2s² 2p¹ with a total of five electrons, making it also reactive as it needs three more electrons to fill its outer shell.

Helium's complete electron shell results in its position as possessing the lowest electron configuration, emphasizing its stability compared to the other elements listed.