To find the formulas for the compounds that form from Rb and each of the given polyatomic ions (NO3-, SO4^2-, PO4^3-), we need to consider the charges of the elements involved.
Rb (Rubidium) is a group 1 element with a charge of +1.
Let's go one by one:
1. Compound formed with NO3- (nitrate):
The formula will be RbNO3.
To determine this, we cross the charges of Rb and NO3- ions. Since Rb has a +1 charge and NO3- has a -1 charge, we do not need to use subscripts to balance the charges.
2. Compound formed with SO4^2- (sulfate):
The formula will be Rb2SO4.
To determine this, we cross the charges of Rb and SO4^2- ions. Rb has a +1 charge, and SO4^2- has a -2 charge. In this case, we need two Rb ions to balance the charge of SO4^2-.
3. Compound formed with PO4^3- (phosphate):
The formula will be Rb3PO4.
To determine this, we again cross the charges of Rb and PO4^3- ions. Rb has a +1 charge, and PO4^3- has a -3 charge. In this case, we need three Rb ions to balance the charge of PO4^3-.
So, the formulas for the compounds formed between Rb and the given polyatomic ions are:
- RbNO3 (Rubidium nitrate)
- Rb2SO4 (Rubidium sulfate)
- Rb3PO4 (Rubidium phosphate)