The Lewis structure of PF3 shows that the central phosphorus atom has one non bonding and three bonding electron pairs. In this compound each Phosphorus atom contributes 5 valence electrons while each fluoride contributes 7 valence electrons making a total of 26 valence electrons. The central Phosphorus atom forms single bonds with each of the fluoride atoms. Phosphorus, therefore ends up with a non-bonding pair since the fluoride atoms already have 8 electrons around them. <span />
Answer: The molecular formula will be 
Explanation:
If percentage are given then we are taking total mass is 100 grams.
So, the mass of each element is equal to the percentage given.
Mass of C= 13.65 g
Mass of F = 86.35 g
Step 1 : convert given masses into moles.
Moles of C =
Moles of F=
Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.
For C = 
For F = 
The ratio of C : F= 1: 4
Hence the empirical formula is
The empirical weight of 
= 1(12)+4(19)= 88g.
The molecular weight = 88.01 g/mole
Now we have to calculate the molecular formula.
The molecular formula will be=
<span>Potassium and rubidium as they are in the same periodic table group as Na</span>
16) you can tell which craters are younger by them being small and you can tell which craters are older by them being larger.
17) The larger craters experienced energetic impacts because they are simply larger in size which makes them being impacted.
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