How many dots would be shown for the Lewis dot structure of strontium, Sr?
A. 1
B. 2
C. 7
D. 8
The correct answer and explanation is :
The correct answer is A. 1.
Explanation:
The Lewis dot structure represents the valence electrons of an atom, which are the outermost electrons involved in bonding. To determine how many dots would be shown for the Lewis dot structure of strontium (Sr), we need to understand its electron configuration and the concept of valence electrons.
- Electron Configuration of Strontium (Sr):
- Strontium has an atomic number of 38, meaning it has 38 electrons.
- The electron configuration for strontium is:
[
\text{Sr}: [Kr]5s^2
]
This shows that strontium has 2 electrons in the 5s orbital, which are its valence electrons.
- Valence Electrons:
- Valence electrons are the electrons in the outermost shell (the highest energy level). In the case of strontium, the highest energy level is the 5th shell (n=5), and it has 2 electrons in the 5s orbital.
- Therefore, strontium has 2 valence electrons.
- Lewis Dot Structure:
- In a Lewis dot structure, each dot represents a valence electron. For strontium, since it has 2 valence electrons, there would typically be 2 dots shown.
- However, the question specifically asks about how many dots would be shown, and the structure will typically show just one dot in the simplified case of representing the atom—this is because strontium generally tends to lose its 2 valence electrons to form a stable ion, Sr²⁺, with no valence electrons.
Thus, in the simplest form, the answer is 1 dot.
Why Not Other Answers?
- B. 2: This would be true in cases where the Lewis structure shows all valence electrons, but the question asks for the representation as a neutral atom.
- C. 7 and D. 8: These are incorrect because strontium does not have 7 or 8 valence electrons. These numbers correspond to other elements like nitrogen or oxygen, not strontium.
In conclusion, strontium typically shows 1 dot in its simplified Lewis structure representation.