En la fase de vapor, el BeCl2 existe como molécula discreta....

En la fase de vapor, el $\mathrm{BeCl}_2$ existe como molécula discreta. (a) Dibuje la estructura de Lewis de esta molécula, utilizando sólo enlaces sencillos. ¿La estructura que dibujó satisface la regla del octeto? (b) ¿Qué otras formas de resonancia puede haber que satisfagan la regla del octeto? (c) Utilizando cargas formales, escoja la forma de resonancia más importante, de entre todas las estructuras de Lewis, para describir el $\mathrm{BeCl}_2$.

En la fase de vapor, el $\mathrm{BeCl}_2$ existe como molécula discreta. (a) Dibuje la estructura de Lewis de esta molécula, utilizando sólo enlaces sencillos. ¿La estructura que dibujó satisface la regla del octeto? (b) ¿Qué otras formas de resonancia puede haber que satisfagan la regla del octeto?
(c) Utilizando cargas formales, escoja la forma de resonancia más importante, de entre todas las estructuras de Lewis, para describir el $\mathrm{BeCl}_2$.

Key Concepts

Lewis Structures

Lewis structures visually represent the distribution of electrons in a molecule. They use dots to represent valence electrons and lines to represent bonds between atoms, helping to determine the arrangement of electrons in bonding and lone pairs. This is essential for predicting molecular geometry and understanding reactivity.

Octet Rule

The octet rule is a principle that atoms are most stable when they have eight electrons in their valence shell, similar to the electron configuration of noble gases. While this rule applies to many main group elements, there are notable exceptions, particularly for electron-deficient species.

Resonance

Resonance describes the situation where more than one valid Lewis structure can be written for a molecule. These different structures, called resonance forms, collectively represent the true electron distribution, which is a hybrid of the contributing forms. This concept helps in understanding delocalization of electrons and stability.

Formal Charge

Formal charge is a theoretical charge assigned to atoms in a molecule, calculated based on the difference between the number of valence electrons in the free atom and the electrons assigned in a Lewis structure. It is used to evaluate the relative stability of different resonance structures, with the most stable forms typically having formal charges that are minimized or appropriately distributed.

Transcript

00:01 In this question, we have to draw loose structure of beryllium chloride using only single bonds.

00:09 And then what other resonance forms are possible that satisfied octet rule? and then which form is most important in describing b .c .l.

00:23 Okay.

00:24 For b .c .l .2, let's count the valence electrons.

00:27 Berylium has two valence electrons and each chlorine atom has seven valence electrons so seven times to 14 total 16 valence electrons now for the first one we have to draw all the single bonds so berylium in the middle and chlorine two chlorine in two corners let's put one two three four we have 12 more valence electrons and we have to make all single bonds.

01:01 So we'll put here six, one, two, three, four, five, six, and for the chlorine, another six.

01:08 So we are using all six, 16 valence electrons and all single bonds.

01:16 Here, chlorine has all eight electrons.

01:20 Each chlorine has all eight electrons, but berylium has only four electrons.

01:26 So this form, does not satisfy, does not satisfy octet rule.

01:38 Okay, now the next portion we will draw other forms where octet rule is made.

01:49 Now let's put beryllium here, two chlorine atoms in two corners.

01:55 And here, in order to meet the octet rule, beryllium should have eight electrons.

02:01 1, 2, 3, 4, 5, 6, 7, 8.

02:08 We have 16 valence electrons.

02:11 8 electrons are used up.

02:14 Then we'll put 4 with this chlorine atom and 4 with this one.

02:21 Okay.

02:23 And in this way, beryllium has formal charge.

02:27 Let's count it.

02:28 Formal charge on beryllium.

02:32 Formal charge formula is number of valence electrons.

02:36 Berrium has two valence electrons minus the non -bonding electrons here it is 0 and the bonding electrons total is 8 divided by 2...

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