Answer:
Explanation:
All three lighter boron trihalides, BX3 (X = F, Cl, Br), form stable adducts with common Lewis bases. Their relative Lewis acidities can be evaluated in terms of the relative exothermicities of the adduct-forming reaction. Such measurements have revealed the following sequence for the Lewis acidity: BF3 < BCl3 < BBr3 (in other words, BBr3 is the strongest Lewis acid).
This trend is commonly attributed to the degree of π-bonding in the planar boron trihalide that would be lost upon pyramidalization (the conversion of the trigonal planar geometry to a tetrahedral one) of the BX3 molecule, which follows this trend: BF3 > BCl3 > BBr3 (that is, BBr3 is the most easily pyramidalized). The criteria for evaluating the relative strength of π-bonding are not clear, however. One suggestion is that the F atom is small compared to the larger Cl and Br atoms, and the lone pair electron in the 2pzorbital of F is readily and easily donated, and overlaps with the empty 2pz orbital of boron. As a result, the [latex]\pi[/latex] donation of F is greater than that of Cl or Br. In an alternative explanation, the low Lewis acidity for BF3 is attributed to the relative weakness of the bond in the adducts F3B-L.
Answer: My guess is D i hope this is right
Explanation:
Answer:
Since they're easy to separate, covalent compounds have low melting and boiling points. 2) Covalent compounds are soft and squishy (compared to ionic compounds, anyway). The reason for this is similar to the reason that covalent compounds have low melting and boiling points. When you hit an ionic compound with something, it feels very hard
Explanation:
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When you add heat to a solid the particles gain energy and start to vibrate faster and faster.
When you add heat to a liquid the particles are given more energy and move faster and faster expanding the liquid.
A cloud that forms on the ground is called fog. Some clouds you see in the sky might be from airplanes. These are called contrails. High level cirrus clouds may travel at speeds up to 100 mph.
