Potassium metal, K, is more reactive than sodium, Na. Calcium, Ca, is less reactive than
sodium. The comparative reactivity of these metals is K > Na > Ca. Explain the reactivity differences of K, Na and Ca based on their atomic structure.
K is larger than Na so it's one electron is more easily removed. The one electron for Na is more easily removed than that from Ca since Ca is harder to remove its two outside electrons (because Ca has a larger positive nuclear charge than Na or K).
Thank you
The differences in reactivity of potassium (K), sodium (Na) and calcium (Ca) can be explained by their atomic structure.
1. Valence electrons: Reactivity is primarily determined by the number of valence electrons in an atom. Potassium, sodium, and calcium all belong to Group 1 of the periodic table, which means they have one valence electron each. However, the distance between the valence electron and the nucleus increases as we move down the group. This causes a weaker attraction between the nucleus and the valence electron, making it easier to lose the electron and increase reactivity.
2. Atomic size: As we move down Group 1, the atomic size increases due to the addition of new energy levels. Potassium has the largest atomic size among the three metals, followed by sodium and then calcium. The larger atomic size leads to a weaker hold on the valence electron, making it easier to be lost during a chemical reaction and thus increasing reactivity.
3. Ionization energy: Ionization energy is the energy required to remove an electron from an atom. As we move down Group 1, the ionization energy decreases due to the increased atomic size and shielding effect. Since potassium has the lowest ionization energy among the three metals, it requires the least energy to remove the valence electron and become a cation, making it the most reactive.
4. Stability of the resulting cation: After losing the valence electron, the resulting cation is more stable if it has a full outer electron shell. In the case of potassium, it loses one electron to achieve the stable electron configuration of argon. Sodium loses one electron to obtain the electron configuration of neon, which is also relatively stable. However, calcium loses two electrons to achieve a stable electron configuration similar to argon. This requires more energy, making calcium less reactive compared to potassium and sodium.
In summary, the reactivity differences of potassium, sodium, and calcium can be explained by their atomic structure, specifically the number of valence electrons, atomic size, ionization energy, and the stability of the resulting cation.
The reactivity of metals depends on the arrangement of electrons in their atomic structure. In the case of potassium (K), sodium (Na), and calcium (Ca), these metals belong to the same group (Group 1) of the periodic table, also known as the alkali metals. The reactivity differences among them can be explained by analyzing their atomic structures.
Potassium has an atomic number of 19, which means it has 19 electrons. These electrons are distributed in different energy levels or shells around the nucleus. The first energy level (closest to the nucleus) can hold a maximum of 2 electrons, while the second energy level can hold a maximum of 8 electrons. Potassium's electron configuration is 2-8-8-1, meaning it has 2 electrons in the first energy level, 8 in the second energy level, 8 in the third energy level, and 1 in the fourth energy level.
Sodium has an atomic number of 11 and its electron configuration is 2-8-1. This means it has 2 electrons in the first energy level, 8 in the second energy level, and 1 in the third energy level.
Calcium has an atomic number of 20, and its electron configuration is 2-8-8-2. This means it has 2 electrons in the first energy level, 8 in the second energy level, 8 in the third energy level, and 2 in the fourth energy level.
The reactivity of alkali metals is primarily determined by the tendency of their outermost electrons to be lost. In the case of potassium, its outermost electron is in the fourth energy level, which is further from the nucleus compared to the outermost electrons of sodium and calcium. As a result, this electron is less strongly attracted to the nucleus and is more easily lost, making potassium more reactive than sodium and calcium.
Sodium's outermost electron is in the third energy level and is closer to the nucleus than in potassium. Therefore, sodium has a lower reactivity compared to potassium.
Calcium, on the other hand, has two electrons in its outermost energy level (fourth energy level). These electrons are even closer to the nucleus compared to sodium's outermost electron, resulting in a stronger attraction to the nucleus. Thus, it is more difficult for calcium to lose its outermost electrons compared to sodium and potassium, making it less reactive than both.
In summary, the reactivity differences among potassium, sodium, and calcium can be explained by considering the arrangement of their outermost electrons within their atomic structures. The farther the outermost electron is from the nucleus, the more easily it can be lost, resulting in higher reactivity.