Bromine can form compounds or ions with any number of fluorine atoms from one to five. Write the

Bromine can form compounds or ions with any number of...

Key Concepts

Steric Number

The steric number is defined as the sum of bonded atoms and lone pairs on a central atom. It is a critical concept in predicting the shape of a molecule because it directly correlates to the number of hybrid orbitals formed and the resulting electron pair geometry, which serves as the starting point for determining the molecular geometry through VSEPR theory.

Hypervalent Molecules

Hypervalent molecules are species in which the central atom accommodates more than eight electrons in its valence shell. This phenomenon is common for elements in the third period and beyond, where available d orbitals (or multi-center bonding descriptions) help to explain bonding in such expanded valence systems. Hypervalency requires special consideration when assigning electron geometry, hybridization, and oxidation states.

Hybridization

Hybridization is a model that describes the mixing of atomic orbitals to form new hybrid orbitals, which then form sigma bonds with other atoms. It provides insights into the bonding framework of a molecule and correlates with the molecular and electron geometries predicted by VSEPR theory, as the number of hybrid orbitals corresponds to the steric number of the central atom.

VSEPR Theory

Valence Shell Electron Pair Repulsion (VSEPR) Theory is used to predict the geometry of individual molecules based on the repulsion between electron pairs (both bonding and lone pairs) around a central atom. It helps in determining both the electron pair geometry (the overall arrangement of all electron pairs) and the molecular geometry (the arrangement of only the atoms) by minimizing repulsive interactions.

Electron Geometry and Molecular Geometry

Electron geometry refers to the spatial arrangement of all electron groups (bonding pairs and lone pairs) around a central atom, while molecular geometry considers only the positions of the atoms. The distinction is critical when lone pairs are present, as they can alter the observed shape of the molecule. Common geometries include linear, trigonal planar, tetrahedral, trigonal bipyramidal, and octahedral arrangements.

Transcript

00:01 All right, so this one could be a little bit tricky because it says compounds or ions.

00:05 So we're kind of going to have to take a guess at what the charge is.

00:08 Compounds would be neutral and ions could be positive or negative.

00:13 So what we're going to see here is whenever we have a bromine with an odd number of fluorine atoms, we'll have an even number of electrons and we won't need to introduce any sort of charges to it to make a molecule that makes sense.

00:27 Whenever we have a bromine with an even number of foreign atoms, that'll be two and four.

00:33 We'll need to put a charge in there, or we'll have an electron that's all by himself.

00:38 So let's jump right in with the first one, brf1.

00:45 So bromine and fouring each like to form one bond.

00:49 So that's really easy to do because they have seven valence electrons.

00:54 It looks just like this.

00:55 It looks sort of like br2 or f2, but just one or the other.

00:59 So this is going to be sp3 hybridization.

01:05 And it's also going to form a linear compound.

01:09 For brf2, we're going to encounter this odd number of electron issue first.

01:16 So if we fill out forin's electrons like this, now bromine has seven valence electrons.

01:24 Two of them are tied up in bonds.

01:26 So we have five left over.

01:30 If i put this fifth one in here, we see that we have an odd one.

01:33 Number and we've also violated the octet rule.

01:36 So we're going to instead remove that and just go with brf2 plus as our molecule.

01:44 Since bromine can expand its octet, it could be a reasonable guess to also try brf2 minus.

01:50 You'll get a different geometry than what i do, but it's still a valid structure.

01:56 So over here, again, this is going to be sp3 hybrid, and it's going to form a bent structure.

02:05 This is analogous to water here, where you have an oxygen with two electrons and two bonds.

02:14 For brf3, what we're going to see is our first time that we have to expand our octet, because bromine, again, has seven valence electrons...

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