Elements are organized on the periodic table based on their properties. Which statement correctly predicts and explains the chemical reactivity of two different metals?

Question

Barium (Ba) is less reactive than calcium (Ca) because the valence electrons in calcium atoms are farther from the nuclei and harder to remove.
Strontium (Sr) is more reactive than magnesium (Mg) because the valence electrons in strontium atoms are farther from the nuclei and harder to remove.
Rubidium (Rb) is more reactive than sodium (Na) because the valence electrons in sodium atoms are closer to the nuclei and easier to remove.
Lithium (Li) is less reactive than potassium (K) because the valence electrons in lithium atoms are closer to the nuclei and harder to remove.

Answer 1

Let's evaluate the statements regarding the reactivity of metals in the context of the periodic table:

1. Barium (Ba) is less reactive than calcium (Ca) because the valence electrons in calcium atoms are farther from the nuclei and harder to remove.
   This statement is incorrect. Barium (Ba) is actually more reactive than calcium (Ca) because it is located lower in Group 2 of the periodic table. As you go down the group, the valence electrons are farther from the nucleus and this makes them easier to remove, increasing reactivity.

2. Strontium (Sr) is more reactive than magnesium (Mg) because the valence electrons in strontium atoms are farther from the nuclei and harder to remove.
   This statement is also incorrect. Strontium (Sr) is more reactive than magnesium (Mg), but it's because the valence electrons in strontium are farther from the nucleus, making them easier to remove, not harder.

3. Rubidium (Rb) is more reactive than sodium (Na) because the valence electrons in sodium atoms are closer to the nuclei and easier to remove.
   This statement is incorrect as well. Rubidium (Rb) is indeed more reactive than sodium (Na), but the reason is because rubidium's valence electron is farther from the nucleus, making it easier to remove, not sodium’s.

4. Lithium (Li) is less reactive than potassium (K) because the valence electrons in lithium atoms are closer to the nuclei and harder to remove.
   This statement is also incorrect. Lithium (Li) is less reactive than potassium (K) because lithium has its valence electron closer to the nucleus and it requires more energy to remove compared to potassium, where the valence electron is further away and easier to remove.

In summary, all statements given are incorrect regarding the reasoning for the reactivity of the metals listed. Reactivity generally increases down a group as the atomic size increases and the valence electrons are farther from the nucleus, making them easier to lose.