# What ions do strontium and calcium metal commonly form?

Where do $\text{strontium}$ and $\text{calcium}$ metal lie in the Periodic Table?
Both metals are alkaline earths; they lie in Group 2 of the Periodic Table. Because the modern Periodic Table reflects electronic structure, each metal has 2 valence electrons. And thus (i) upon oxidation they commonly form ${M}^{2 +}$ ions; and (ii) the chemistry of both metals should be to a first approximation similar.
The isotope ""^90Sr is a radioactive isotope with a short half-life, and this is a dangerous isotope in that it can replace calcium in the human body and cause radioactive poisoning.