What element has eight protons?

Orbitals are different shapes. For example, the s orbital is shaped like a sphere, while the p orbital is shaped like a dumbbell.

Electrons usually fill the lowest energy levels first. If electrons were filling a theater to see a performance, they would all take seats in the front row until it was full, then move on to the second row, and so on. There is a limit to the number of electrons that can inhabit each energy level. The first energy level holds up to two electrons, and the second energy level can hold up to eight electrons.

The formula 2 × n 2 , where n = the energy level, can be used to figure out how many electrons each energy level can hold. Using this formula, we know that the third energy level can hold up to 18 electrons (2 × 3 2 = 18).

Thousands of years ago, ancient Greek philosophers believed that all matter was made from combinations of just four elements—earth, water, air, and fire. Although we know today that they were wrong, the idea that elements are the basis of all matter is actually true. An element is something that cannot be broken down into a simpler substance. It is something that is made up of only one type of atom. To date, scientists have discovered 118 different elements. These 118 elements combine to make millions of different substances. Some elements, such as gold, copper, and carbon, have been known for thousands of years. Others, such as livermorium, have been discovered recently. In the future, even more elements might be discovered.

Electron Configuration

To describe the electrons in an atom, scientists use a notation called an electron configuration:

n (type of orbital) number of electrons

A hydrogen atom has only one electron, which can be found in the first energy level (1), in the s orbital. Its electron configuration can be written as 1s 1 and looks like this:

H

The atom beryllium has four electrons, two in the first energy level and two in the second. Therefore, beryllium’s electron configuration is 1s 2 2s 2 . It looks like this:

Be