[Campbell Biology P.84] An unknown element, Element X, is found to have 2 electrons in its ... | Practice Question

An unknown element, Element X, is found to have 2 electrons in its first shell and 6 electrons in its second and outermost shell. Based on the principles described in the text, how would you classify Element X's chemical reactivity?

  • A: It is likely to be inert because it has 6 valence electrons, which is a stable number.
  • B: It is chemically reactive because its valence shell is incomplete.
  • C: It is chemically reactive because its first shell is full.
  • D: It would form compounds similar to Neon.

Explanation

Element X has 6 electrons in its second shell, which is the outermost valence shell. The text states that the second shell holds a maximum of 8 electrons. Since 6 is less than 8, its valence shell is incomplete. The text also clearly states: 'All the other atoms in Figure 2.7 are chemically reactive because they have incomplete valence shells.'