A student is investigating the properties of a hypothetical element, 'X', which has an electron configuration ending in 4d⁷. Based on its position in the periodic table, what is the most likely charge that element 'X' will form in its most common stable ion?
- A+3
- B+4
- C+2
- D+1
Show answer & explanationAnswer & explanation
Correct answer: C. +2
An electron configuration ending in 4d⁷ indicates a transition metal. Transition metals typically lose electrons from their outermost s-orbital first, followed by d-orbital electrons if necessary. For an element with 4d⁷, the preceding s-orbital would be 5s. Most transition metals, especially in the middle of the d-block, commonly form +2 ions by losing their two outermost s-electrons (in this case, 5s²). While other oxidation states are possible for transition metals, +2 is a very common and stable oxidation state.
Why the other options are wrong
- A. While +3 is possible for some transition metals, +2 is highly prevalent due to the loss of the two s-electrons.
- B. +4 is less common and would require losing more d-electrons, often seen in specific compounds like oxides.
- D. +1 is less common for d⁷ elements, usually seen for Cu or Ag in specific contexts.
Transition Metal Ion Formation
Transition metals typically form cations by first losing electrons from their outermost s-orbital, followed by d-orbital electrons if higher oxidation states are required.
- Electrons are removed from the s-subshell before the d-subshell.
- Many transition metals form +2 ions by losing their two valence s-electrons.
- Multiple oxidation states are common due to the involvement of d-electrons.
Memory trick: S-shell First, Then D-shell.