A typical hydrogen atom has one proton and one electron. The electron orbiting the nucleus occupies the first energy level.
Mass number: 1
An atom of helium has two protons, tow neutrons and two electrons. The two electrons orbit in the same energy level.
Atomic number: 2
Mass number: 4
(2 protons + 2 neutrons)
A lithium atom has three protons, three neutrons and three electrons. The first energy level can hold only tow electrons, so the third electron occupies a second energy level.
Atomic number: 3
Mass number: 6
(3 protons + 3 neutrons)
A neon atom has 10 protons, 10 neutrons, and 10 electrons. The second level can hold up to eight electrons; thus, both the first and second energy levels are filled.
Atomic number: 10
Mass number: 20
(10 protons + 10 neutrons)
Please allow access to your computer’s microphone to use Voice Recording.
We can’t access your microphone!
Click the icon above to update your browser permissions and try again
Reload the page to try again!
Press Cmd-0 to reset your zoom
Press Ctrl-0 to reset your zoom
It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.
Your microphone is muted
For help fixing this issue, see this FAQ.