Atoms with the same chemical properties as calcium are those in the same group (vertical column) of the periodic table. This is because elements in the same group have the same number of valence electrons, which are the electrons in the outermost shell and responsible for chemical bonding.

Calcium (Ca) belongs to Group 2, also known as the alkaline earth metals. So, atoms that have similar chemical properties to calcium include:

* Beryllium (Be)

* Magnesium (Mg)

* Strontium (Sr)

* Barium (Ba)

* Radium (Ra)

These elements will all share similar reactivity, forming similar types of compounds, and exhibiting similar ionic charges.