Reactivity Series and Periodic Table: Understanding the Elements
Which of the following statements is true?
K is more reactive than Ca because K has to gain only one electron to complete its outermost shell.
K is more reactive than Ca because K has to lose only one electron to complete its outermost shell.
Mg is more reactive than Na because Mg has to lose only one electron to complete its outermost shell.
Mg is more reactive than Na because Mg has to gain only one electron to complete its outermost shell.
Answer:
K is more reactive than Ca because K has to lose only one electron to complete its outermost shell.
Potassium (K) is a chemical element with atomic number 19, meaning it has 19 electrons. The electron configuration of potassium is 1s²2s²2p⁶3s²3p⁶4s¹, indicating that it has a single valence electron in its outer shell. This valence electron is the key factor in determining potassium's reactivity.
The reactivity series is an arrangement of metals based on their reactivity from highest to lowest. Alkali metals, such as potassium, belong to the highest reactivity group. They readily lose one electron in chemical reactions to achieve a stable electron configuration. In the case of potassium, losing one electron allows it to attain a full outermost shell, making it highly reactive.
On the other hand, calcium (Ca) belongs to the second column of the periodic table, which includes alkaline earth metals. These metals have higher ionization energy compared to alkali metals, as they need to lose two electrons to achieve a stable electron configuration. This makes calcium less reactive than potassium, as potassium only needs to lose one electron to complete its outermost shell.