Chromium is a metal. Atomic number of it is 24.
The oxidation number for Cr in Cr2O7^2- is +6.
The change in oxidation number of Cr depends on the specific reaction or compound involved. For example, in the reaction from Cr(III) to Cr(VI), the oxidation number of Cr changes from +3 to +6, indicating an increase in oxidation state.
+3 for Cr and -2 for O
+2 for Ca, +6 for Cr, -2 for each O
In CrBr (chromium monobromide) Cr would have an oxidation number of +1. This compound is not known perhaps you meant CrBr3, where chromium has an oxidation number of +3
Hydrogen has the atomic number of 1.
Aluminum (Al)
Li is atom number three, not only 'was' but it still is and ever will be.
Atomic not Atomis!
The oxidation number for Cr in Cr2O7^2- is +6.
The change in oxidation number of Cr depends on the specific reaction or compound involved. For example, in the reaction from Cr(III) to Cr(VI), the oxidation number of Cr changes from +3 to +6, indicating an increase in oxidation state.
the answer is 107.87
The atomic number tells you the number of protons the atom of an element has. The atomis is the smaller of the two numbers next to symbol of the element.
+3 for Cr and -2 for O
Atomis
+2 for Ca, +6 for Cr, -2 for each O
.400 moles