How many bromine (Br) atoms are present in 2.50 g of elemental bromine?

• A. 9.44 × 10^{21} atoms
• B. 4.22 × 10^{20} atoms
• C. 2.11 × 10^{23} atoms
• D. 1.51 × 10^{22} atoms

Answer: (A)

Verified step by step guidance

1. Identify the chemical form of elemental bromine. Elemental bromine exists as diatomic molecules, Br\_2, meaning each molecule contains 2 bromine atoms.
2. Calculate the number of moles of Br\_2 molecules in 2.50 g of bromine using the molar mass of Br\_2. The molar mass of Br is approximately 79.90 g/mol, so for Br\_2 it is \$2 \times 79.90 = 159.80\( g/mol. Use the formula: \)\text{moles of Br}_2 = \frac{\text{mass of Br}_2}{\text{molar mass of Br}_2}$.
3. Determine the number of Br\_2 molecules by multiplying the moles of Br\_2 by Avogadro's number, \$6.022 \times 10^{23}\( molecules/mol: \)\text{number of molecules} = \text{moles of Br}_2 \times 6.022 \times 10^{23}$.
4. Since each Br\_2 molecule contains 2 bromine atoms, multiply the number of Br\_2 molecules by 2 to find the total number of bromine atoms: \(\text{number of Br atoms} = 2 \times \text{number of Br}_2 \text{ molecules}\).
5. Express the final answer in scientific notation to match the format of the given options.