Argon (Ar) and calcium (Ca) do not have the same atomic mass. The atomic mass of argon is approximately 39.95 atomic mass units (u), while the atomic mass of calcium is approximately 40.08 u. Although these values are close, they are not exactly the same.
The atomic mass of an element is determined by the average mass of all the naturally occurring isotopes of that element, taking into account their relative abundance. Isotopes are atoms of the same element that have different numbers of neutrons in their nuclei.
Argon has three naturally occurring isotopes: ^36Ar, ^38Ar, and ^40Ar. The most abundant isotope is ^40Ar, which makes up about 99.6% of naturally occurring argon. The atomic mass of argon is mainly influenced by the mass of ^40Ar.
Calcium also has several isotopes, with the most abundant being ^40Ca, ^42Ca, ^43Ca, ^44Ca, and ^46Ca. However, ^40Ca is the most abundant isotope, making up around 96% of naturally occurring calcium. The atomic mass of calcium is primarily determined by the mass of ^40Ca.
While the atomic masses of argon and calcium are similar, they are not the same due to the different isotopic compositions of these elements.