To determine the bond pairs in the \(\text{BF}_4^-\) ion, we first analyze its structure and bonding:
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Determine the central atom and its connectivity: Boron (B) is the central atom, and it is bonded to four fluorine (F) atoms.
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Count the valence electrons:
- Boron has 3 valence electrons.
- Each fluorine has 7 valence electrons, and since there are four fluorine atoms: \(4 \times 7 = 28\).
- The \( \text{BF}_4^- \) ion carries an extra electron due to its negative charge.
Total valence electrons = \(3 + 28 + 1 = 32\).
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Distribute electrons to form bonds:
- Boron forms a single bond with each of the four fluorine atoms. Each single bond consists of 2 electrons.
- Therefore, 4 bonds will use \(4 \times 2 = 8\) electrons.
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Calculate the remaining electrons:
- Total used for bonding = 8
- Remaining electrons = \(32 - 8 = 24\).
- These remaining electrons are typically found as lone pairs on the fluorine atoms.
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Bond pairs: Each bond between boron and fluorine atoms represents one bond pair. Since there are 4 single bonds between B and F, the number of bond pairs is:
- Bond pairs = 4.
In summary, the \(\text{BF}_4^-\) ion has 4 bond pairs.
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