To determine which atom will lose its electron most reluctantly, we need to consider the relationship between atomic size and ionization energy. Ionization energy is the energy required to remove an electron from an atom. Generally, the larger the atomic size, the lower the ionization energy, because the outermost electrons are further from the nucleus and experience less electrostatic attraction. ### Step-by-Step Explanation: 1. **Understanding Atomic Size and Ionization Energy**: - Atomic size increases down a group in the periodic table because additional electron shells are added. This means that the outermost electrons are further from the nucleus. - As atomic size increases, the effective nuclear charge felt by the outermost electrons decreases, making it easier to remove these electrons. Therefore, larger atoms typically have lower ionization energies. 2. **Analyzing the Given Order of Sizes**: - The order of the elements based on size is: R < T < W < X < Y. This means: - R is the smallest atom. - Y is the largest atom. - Since Y is the largest, it will have the lowest ionization energy, meaning it will lose its electron most easily. 3. **Identifying the Reluctance to Lose Electrons**: - Conversely, R, being the smallest atom, will have the highest ionization energy among the five. This means that R will lose its electron most reluctantly because its outermost electron is held more tightly by the nucleus due to the smaller atomic radius and higher effective nuclear charge. 4. **Evaluating the Options**: - **Option A: R** - This is the correct answer. R is the smallest atom and will have the highest ionization energy, making it the most reluctant to lose its electron. - **Option B: T** - T is larger than R, so it will have a lower ionization energy than R, making it more willing to lose its electron. - **Option C: W** - W is larger than T and will have an even lower ionization energy, thus losing its electron more readily than R. - **Option D: X** - X is larger than W and will also have a lower ionization energy, making it even less reluctant to lose its electron compared to R. ### Summary of Why Other Options are Incorrect: - **T, W, and X** are all larger than R, which means they have lower ionization energies and will lose their electrons more easily than R. Therefore, they are not the correct answer. ### Common Pitfalls: - Students may confuse atomic size with ionization energy, thinking that larger atoms are more reluctant to lose electrons. Remember, larger atoms generally lose electrons more easily due to lower ionization energies. - It’s important to focus on the specific order of sizes given in the question, as this directly influences the ionization energy. ### Revision Summary: - **Ionization energy increases with decreasing atomic size**; smaller atoms hold their electrons more tightly. - **R is the smallest atom** in the given order, making it the most reluctant to lose its electron. - **Larger atoms (T, W, X, Y)** have lower ionization energies and lose electrons more readily. - **Always relate atomic size to ionization energy** when answering questions about electron loss.