Atoms with the same chemical properties as calcium will be found in the same group of the periodic table. This is because elements in the same group have the same number of valence electrons, which are the electrons involved in chemical bonding.

Calcium (Ca) is in Group 2, also known as the alkaline earth metals. Therefore, other alkaline earth metals will have similar chemical properties. These include:

* Beryllium (Be)

* Magnesium (Mg)

* Strontium (Sr)

* Barium (Ba)

* Radium (Ra)

Why they have similar properties:

All these elements have two valence electrons. This means they tend to lose these two electrons to form a +2 cation, which is why they are all reactive metals. They also share similar reactivity patterns and form similar types of compounds.

However, it's important to note that there will be some differences in reactivity due to their varying atomic sizes and ionization energies. For instance, calcium is more reactive than magnesium, and barium is more reactive than calcium.