Which of the following is the Lewis dot structure for the lithium ion?
a) [:Li:]²⁻
b) [Li]⁺
c) [:Li]⁻
d) [Li]²⁺
e) [:Li]⁺
The Correct answer and Explanation is:
The correct answer is e) []⁺.
Explanation:
The Lewis dot structure is a visual representation that shows the valence electrons of an atom. Lithium (Li), which is in Group 1 of the periodic table, has one valence electron. In its elemental form, the Lewis structure can be represented simply as [], where the dot indicates the single valence electron. However, when lithium loses an electron to form a lithium ion (Li⁺), it becomes positively charged due to the loss of this valence electron.
- Understanding Ion Formation: Lithium has an atomic number of 3, meaning it has three protons and, in its neutral state, three electrons. The electronic configuration is 1s² 2s¹, with one electron in its outermost shell. To achieve a stable electron configuration similar to that of noble gases, lithium tends to lose this one valence electron, resulting in a +1 charge, thus forming the lithium ion (Li⁺).
- Lewis Structure for Li⁺: The Lewis dot structure for the lithium ion is depicted as []⁺. The colon indicates the absence of a dot (representing the lost electron) next to lithium, showing that it has no valence electrons left. The plus sign indicates the positive charge of the ion.
- Eliminating Other Options:
- a) [:Li:]²⁻ and c) []⁻ both suggest that lithium has gained electrons, which is incorrect for a lithium ion.
- b) [Li]⁺ does not represent the valence electrons at all, as it does not include the Lewis dot structure.
- d) [Li]²⁺ implies that lithium has lost two electrons, which is not possible as it can only lose one.
In summary, the correct representation of the lithium ion using the Lewis dot structure is []⁺, which accurately reflects its positive charge and lack of valence electrons after ionization. This understanding of Lewis structures is crucial in predicting how atoms interact and form compounds in chemistry.