Use the δ+/ δ- convention to indicate the direction of...

Use the $\delta+/ \delta$ - convention to indicate the direction of expected polarity for each of the bonds indicated. (a) $\mathrm{H}_{3} \mathrm{C}-\mathrm{Cl}$ (b) $\mathrm{H}_{3} \mathrm{C}-\mathrm{NH}_{2}$ (c) $\mathrm{H}_{2} \mathrm{~N}-\mathrm{H}$ (d) $\mathrm{H}_{3} \mathrm{C}-\mathrm{SH}$ (e) $\mathrm{H}_{3} \mathrm{C}-\mathrm{MgBr}$ (f) $\mathrm{H}_{3} \mathrm{C}-\mathrm{F}$

Use the $\delta+/ \delta$ - convention to indicate the direction of expected polarity for each of the bonds indicated.
(a) $\mathrm{H}_{3} \mathrm{C}-\mathrm{Cl}$
(b) $\mathrm{H}_{3} \mathrm{C}-\mathrm{NH}_{2}$
(c) $\mathrm{H}_{2} \mathrm{~N}-\mathrm{H}$
(d) $\mathrm{H}_{3} \mathrm{C}-\mathrm{SH}$
(e) $\mathrm{H}_{3} \mathrm{C}-\mathrm{MgBr}$
(f) $\mathrm{H}_{3} \mathrm{C}-\mathrm{F}$

Key Concepts

?+/?- (Delta) Notation Convention

The ?+/?- notation is used to denote the distribution of partial charges in a polar covalent bond. The atom with a higher electronegativity is assigned a ?- (partial negative) charge, while the other atom, with a lower electronegativity, is assigned a ?+ (partial positive) charge. This convention helps in predicting intermolecular interactions and reactivity.

Electronegativity

Electronegativity is the measure of an atom's ability to attract electrons in a chemical bond. Differences in electronegativity between two bonded atoms lead to an uneven distribution of electron density, which in turn creates partial positive and negative charges on the atoms.

Polar Covalent Bond

A polar covalent bond is formed when two atoms share electrons unequally due to a difference in their electronegativities. This unequal sharing results in partial charges (?+ and ?-) on the atoms, which influences the physical and chemical properties of the compound.

Transcript

00:01 We want to use the delta positive and delta negative convention to indicate the direction of the expected polarity for each of these bonds here.

00:09 Now, we will have something being delta positive.

00:16 So this is a slight positive charge.

00:18 So that means it's going to be the less electro negative of the two atoms.

00:26 And then delta negative means it's going to have a slight negative charge on it.

00:30 So that means it's going to be more electronegative.

00:36 And that kind of makes sense, because remember, electro negativity is talking about how much it wants to kind of surround itself with electrons in some sense.

00:44 So if we're pulling more of something negative towards us, it should be more negatively charged.

00:56 Now, one trend that may help us with this is that going across, cross a row for the most part is going to cause us to be more electronegative.

01:09 And going up the column is going to also cause us to be more electronegative.

01:14 And you might see there's a couple of places where that's not necessarily true.

01:17 It's specifically right here.

01:19 But you see for the vast majority outside of that little island, it follows on the main part of the periodic table.

01:30 So let's go ahead and see if we can apply that to the first one.

01:33 We have carbon to chlorine.

01:34 So carbon's here, chlorine's here.

01:36 So that's not necessarily going to be something we can compare.

01:40 And a quick way to kind of remember, anytime we're comparing anything with these ones marked in red here, then the one in red is more than likely going to be more electronegative.

01:54 So we're comparing carbon and chlorine.

01:57 So you can even see there, chlorine is 3.

01:59 Carbon is 2 .5.

02:01 So that means the chlorine is going to be more electronegative.

02:05 So that's going to get the delta negative, and the carbon is going to get the delta positive.

02:11 Now for b, we can actually apply our trend, because notice how carbon is to the left of nitrogen.

02:21 So that's going to tell us that nitrogen is more electronegative, so it's going to be the delta negative.

02:29 And then the carbon is going to have a slight partial charge, or a slight positive partial charge, so it's going to be delta positive...

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