whats the correct formula for

1. rubidium selenide

2. potassium phosphate

Rb2Se

Phosphate is PO3-3
and Potassium is K+1

so what is the formula for potassium phosphate? We will be happy to critique your thinking.

Bob P made a tiny typo. Phosphate is PO4^-3

thanks

is it K3PO4?

yes

To determine the correct formula for a compound, you need to balance the charges of the elements involved. Both rubidium selenide and potassium phosphate consist of a metal cation (rubidium or potassium) and a non-metal anion (selenide or phosphate).

1. Rubidium is a Group 1 metal, which means it has a charge of +1. Selenide is a non-metal from Group 16, which means it has a charge of -2. To balance the charges, you need two rubidium ions (+1) to combine with one selenide ion (-2). Therefore, the formula for rubidium selenide is Rb2Se.

2. Potassium is also a Group 1 metal with a charge of +1. Phosphate is a polyatomic ion with a charge of -3. Similar to the first example, you need three potassium ions (+1) to combine with one phosphate ion (-3) to balance the charges. Hence, the formula for potassium phosphate is K3PO4.

Remember, when writing chemical formulas, it's essential to balance the charges of the ions to achieve neutrality.