Assertion: calcium ion's number | /r/HasProperty | atoms of the same element
Facets:
Source sentences:
text: Number of isotopes (atoms of the same element with a different number of neutrons): 24; 5 stable
text: Number of isotopes (atoms of the same element with a different number of neutrons): 28 whose half-lives are known; 4 stable
text: Number of isotopes (atoms of the same element with a different number of neutrons): 21; 1 stable