Final answer:
To find the atomic number of atom A with the given electron configuration, we sum the number of electrons in each orbital (2 in 1s, 2 in 2s, 9 in 2p, and 1 in 3s), which totals to 14 electrons. Therefore, the atomic number is 14, which does not match any provided options, suggesting a typo in the question.
Step-by-step explanation:
The question asks about determining the atomic number of atom A based on its electron configuration: 1s² 2s² 2p⁹ 3s¹.
Each electron configuration notation shows the distribution of electrons among the different energy levels and subshells. To find the atomic number, we simply count the total number of electrons in a neutral atom, which is the same as the number of protons in the nucleus.
For atom A, we count the electron in each energy level and subshell:
- 1s² implies 2 electrons
- 2s² implies 2 electrons
- 2p⁹ implies 9 electrons
- 3s¹ implies 1 electron
Summing these up, 2+2+9+1 equals 14 electrons in total. Therefore, the atomic number of atom A is 14, which matches none of the answer choices provided in the question, indicating a possible typo in the question itself. The atomic number should refer to the number of protons, and hence the number of electrons in a neutral atom.