What is the correct formula for lithium fluoride?
A. LiF
B. Li2F2
C. Li3F9
D. LiF7
E. Li7F19
The correct answer and explanation is:
The correct formula for lithium fluoride is A. LiF.
Explanation:
Lithium fluoride is a simple ionic compound made up of lithium (Li) and fluorine (F) atoms. The formula LiF reflects the combination of one lithium ion (Li⁺) and one fluoride ion (F⁻).
- Lithium (Li) is an alkali metal, which typically forms a +1 cation by losing one electron. This gives the lithium ion a charge of +1.
- Fluorine (F) is a halogen, and it tends to gain one electron to form a -1 anion, called fluoride (F⁻).
When these two ions combine, the charges balance each other out. Lithium gives away one electron, and fluorine accepts it, resulting in a neutral ionic compound. This leads to the formula LiF, which indicates one lithium ion combined with one fluoride ion.
- LiF is an example of an ionic bond where oppositely charged ions attract each other, forming a stable compound. The compound forms a crystalline lattice structure that is stable and has a high melting point.
The other options are incorrect because:
- Li2F2 would imply two lithium ions for every two fluoride ions, which would still not be the most stable ratio.
- Li3F9 and Li7F19 would suggest much larger proportions of lithium to fluoride, which are not typical for lithium fluoride compounds.
- LiF7 is also incorrect, as no such stoichiometric ratio exists for lithium fluoride in standard chemical practice.
In summary, lithium fluoride is a simple and stable ionic compound represented by LiF, reflecting the 1:1 ratio of lithium ions to fluoride ions.