What is the atomic number of the element Strontium?

The story behind the answer

The atomic number is the number of protons in an element’s nucleus; strontium (symbol Sr) has 38 protons, so its atomic number is 38. For comparison, 47 is silver (Ag), 11 is sodium (Na), and 73 is tantalum (Ta).

Strontium is an alkaline earth metal (group 2), sitting below calcium and above barium. It’s famous for giving fireworks their vivid red color, and certain isotopes (like Sr-89) are used in medicine for bone pain relief. Memory tip: going down group 2, the atomic numbers jump by 18 as you pass the transition metals—Calcium 20 → Strontium 38 → Barium 56. So, think “Ca 20, add 18 to get Sr 38,” locking in strontium’s 38.