Write Lewis structures for the following: (a) H2 (b) HBr (c)...

Key Concepts

Valence Electron Counting

This concept involves determining the total number of electrons available for bonding in the molecule by summing the valence electrons of all the atoms and adjusting for any charges. Knowing the number of electrons is essential for correctly distributing electrons among bonds and lone pairs in the Lewis structure.

Octet Rule

The octet rule is a guiding principle that atoms prefer to have eight electrons in their valence shell to achieve a stable, noble gas configuration, although there are exceptions like hydrogen and electron-deficient species. This rule helps determine how atoms in a molecule share electrons and form bonds.

Formal Charge

Formal charge is a method used to estimate the distribution of electric charge within a molecule by comparing the number of electrons assigned to an atom in a Lewis structure with its number of valence electrons in the free atom state. Structures with minimized or zero formal charges are generally more stable.

Multiple Bonds

Some molecules require the formation of double or triple bonds to satisfy the octet rule and to distribute electrons appropriately. Multiple bonding helps atoms reach the desired valence electron configuration, and recognizing when to form such bonds is key in constructing accurate Lewis structures.

Resonance Structures

Some molecules can be represented by two or more valid Lewis structures that differ only in the placement of electrons, not the arrangement of atoms. Understanding resonance is important as it provides insight into the electron delocalization and stability of the molecule.

Transcript

00:01 Okay, so we want to draw a little structure for the following.

00:03 The first one is hydrogen gas, and hydrogen has one valence electron, so therefore it's going to form one bond, because a bond is two electrons, shared between two atoms.

00:24 The second one is going to be hydrobermic acid, and bromine to halogen, it has seven valence electrons.

00:30 As a result, it's going to form one bond, and we have hydrogen, which can only form one bond, so.

00:41 And then just putting the electron pairs around the bromine.

00:47 Next one is phosphorus trichloride.

00:52 And phosphorus is going to be the central atom because it has five valence electrons.

00:57 As a result, it's going to form three bonds.

01:01 So that'll be the central atom.

01:03 And we're going to orient it like this.

01:05 We're going to have one chlorine in the front, one in the back, and one on the side.

01:14 And this is the preferred way of drawing it because we're going to have two electrons on the phosphorus to have five in total because each bond is one electron.

01:23 And the electrons of phosphorus are going to repel the electrons on chlorine, which is why it's oriented like this instead of, instead of this way.

01:36 We want the electrons to be as far apart from each other as possible.

01:45 And the next one is going to be sulfur diphyluride.

01:55 And sulfur is going to be the central atom because it has also six valence electrons.

02:03 And then just one bond to each of these halogens, drawing the electron pairs around the atoms.

02:09 It's going to have 7 as well.

02:11 And sulfur has 6.

02:13 It's already 1, 2, 3, 4, 5, and 6.

02:23 And the next one is, it's ethylene, it's 2 carbon alken.

02:33 So we can draw like this.

02:36 It's the simplest of the alkenes, and alken is the double bond.

02:40 Each of these carbons are going to have two hydrogens because they're already double bound to each other, and they need four bonds in total.

02:46 And for f this one is going to be di -nitrogen dihydride so n2 h2 and nitrogen needs it has five balanced electrons it needs three bonds to have a complete octet and it's going to be the central atom so we're first going to start with nitrogen and it needs three bonds so we're going to double bond it to another nitrogen because the hydrogen can only form one bond if we put a hydrogen here instead of a nitrogen it'll only be a single bond so we can draw like this, and then just add a hydrogen to each of the nutrients.

03:35 And then just putting the electron pairs, it's going to be one pair for each one.

03:44 X1 is going to be ch2 and each.

03:49 So if it's if it's ch2, it's going to be an alkyne.

03:55 Or it's going to be a double bond to the carbon atom...

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