An unknown element X forms a compound with bromine: XBr. Predict the chemical formula of the compound that element X makes with oxygen. Justify your answer.

why wouldn't it be X2O ?

Correct me if I'm wrong but I think in XBr, the charge of the bromine is -1. It makes the X have a charge of -1. This -1 charge is necessary to make the total charge of the formula be zero. Since O is a -2 and we now know X is a +2, the predicted formula between X and oxygen is X2O. I'm not 100% sure if this is correct, thanks!

Dan, just a word or two to clarify what you wrote and to point out a couple of typos. X2O is correct. My corrections and comments are in bold.

Correct me if I'm wrong but I think in XBr, the charge of the bromine is -1. It makes the X have a charge of -1 (you mean +1). This -1 charge (you mean +1) is necessary to make the total charge of the formula be zero. Since O is a -2 and we now know X is a +2,(it would be better, in my opinion, to say the total charge on X is +2 so each is +1) the predicted formula between X and oxygen is X2O. I'm not 100% sure if this is correct, thanks!

Thank you!

To predict the chemical formula of the compound that element X makes with oxygen, you need to consider the valence electrons and the charges of the elements involved.

First, let's determine the valence electrons of element X. Since it is an unknown element, we don't have specific information about it. However, most elements follow the octet rule, meaning they tend to form compounds in a way that allows them to have eight electrons in their outermost energy level. This is commonly achieved by gaining, losing, or sharing electrons.

Now, let's consider bromine (Br). It belongs to Group 17 (Group VIIA or halogens) of the periodic table and has seven valence electrons. To achieve a stable octet, bromine needs to gain one electron.

Oxygen (O) belongs to Group 16 (Group VIA) and has six valence electrons. To achieve the octet, oxygen needs to gain two electrons.

From this information, we can infer that element X, when forming a compound with oxygen, is likely to lose two electrons to satisfy oxygen's requirement and gain one electron to satisfy bromine's requirement. By doing so, element X achieves a stable octet.

Since we don't know the identity of element X, we'll simply represent it as X. Following the charge requirements, the chemical formula of the compound between element X and oxygen can be predicted as X2O.

It is important to note that this prediction assumes that element X follows the general trends of elements in the periodic table. To confirm the chemical formula of X2O or get a more accurate answer, experimental data or specific information about element X is needed.