Sorry still confused. Here's the problem:

0.249g of a diatomic element occupies a volume of 125mL at 120 degrees Celsius and 2.00 atm. This element IS?

I used PV/RT =n so:
2.00 atm (.125L)/0.0821L*atm/mol*K (393K) = 11.96 then 0.249/11.96 =20.1 which is Neon. It isn't diatomic. PLEASE HELP ME. I'm losing my mind.

You must not be punching the calculator in the right places. I get n = 0.00775 which is a far cry from 11.96.

0.249/0.0075 = about 32.

I understand that you're confused about finding the diatomic element given the information provided. Let's break down the problem step by step to properly solve it.

To determine the diatomic element, we need to calculate the number of moles of the gas and then identify the element based on its behavior as a diatomic gas.

1. Start with the ideal gas law equation, PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature in Kelvin.

2. You correctly used PV/RT = n for your calculation. Let's recheck your calculation.

Given:
Pressure (P) = 2.00 atm
Volume (V) = 125 mL = 0.125 L (since 1 L = 1000 mL)
R = 0.0821 L*atm/(mol*K)
Temperature (T) = 120 °C = (120 + 273) K = 393 K

Substituting these values into the equation:
n = (2.00 atm * 0.125 L) / (0.0821 L*atm/(mol*K) * 393 K)
n = 0.0193 moles

3. Now that we have the number of moles, we can determine the diatomic element. Diatomic elements are those that exist in nature as diatomic molecules (two atoms bonded together), such as hydrogen (H2), nitrogen (N2), oxygen (O2), fluorine (F2), chlorine (Cl2), bromine (Br2), and iodine (I2).

Since you have determined that the molar mass of the gas is 0.249 g, we can calculate its molar mass by dividing the mass by the moles:
Molar mass = 0.249 g / 0.0193 moles ≈ 12.89 g/mol

Looking at the periodic table, we can compare the molar mass value to the known molar masses of the diatomic elements:

- Hydrogen (H2) has a molar mass of approximately 2 g/mol.
- Nitrogen (N2) has a molar mass of approximately 28 g/mol.
- Oxygen (O2) has a molar mass of approximately 32 g/mol.
- Fluorine (F2) has a molar mass of approximately 38 g/mol.
- Chlorine (Cl2) has a molar mass of approximately 71 g/mol.
- Bromine (Br2) has a molar mass of approximately 160 g/mol.
- Iodine (I2) has a molar mass of approximately 254 g/mol.

From the molar mass calculated (12.89 g/mol), we can conclude that the diatomic element in question is hydrogen (H2).

Therefore, the diatomic element you're looking for is hydrogen (H2) rather than neon.

I hope this explanation helps clarify the problem. Let me know if you have any further questions!