Answer
When we name ionic compounds, which is what CaCl$_{2}$ is, we name the first element in the compound and then the second element in the compound, replacing the ending of the second element with $-ide$. Only if we are talking about molecular compounds between nonmetals do we add prefixes to the names of the elements.
With calcium, we do not need to specify the oxidation state because it has only one common oxidation (2+) because it belongs to the alkaline earth metals group. We only specify oxidation state with Roman numerals if the oxidation state is ambiguous as in the transition metals, which may have several oxidation states.
Work Step by Step
When we name ionic compounds, which is what CaCl$_{2}$ is, we name the first element in the compound and then the second element in the compound, replacing the ending of the second element with $-ide$. Only if we are talking about molecular compounds between nonmetals do we add prefixes to the names of the elements. With calcium, we do not need to specify the oxidation state because it has only one common oxidation (2+) because it belongs to the alkaline earth metals group. We only specify oxidation state with Roman numerals if the oxidation state is ambiguous as in the transition metals, which may have several oxidation states.
