[Verse 1] I start with the number that names the element: Eleven protons make sodium every time. For a neutral atom, match with electrons; Eleven negatives balance eleven positives. Use twenty-three for this isotope's mass number; Protons plus neutrons make that sum. Twenty-three minus eleven leaves twelve; Now the nucleus count is done. [Chorus] Enough to make eleven, No extra ones to spare. Two inside, eight next, One in the outer layer. [Verse 2] Our ring picture is a simple model, For the first eighteen in this lesson. It isn't a picture of planetary paths; Real electrons need another description. Valence means electrons in the outer shell. Oxygen's two, six; magnesium's two, eight, two. Helium's full first ring holds only two; A group clue needs that exception too. [Final Chorus] Enough to make eleven, No extra ones to spare. Two inside, eight next, One in the outer layer.
