What is the valence shell electron logarithm, how to find it, and how to find it

Number of valence electron logs.

Refers to the presence of lone pairs of electrons in the molecule.

The number of pairs. Valence shell electrons.

Logarithm = key.

The number of lone electron pairs, where:

The number of lone electron pairs = 1 2 (the number of valence electrons of the central atom - the number of atoms bound to the central atom x how many electrons can be accepted by the bound atom), if it is an anion.

The number of valence electrons of the central atom + the number of charges.

If it's cationic.

The number of valence electrons of the central atom - the number of charges, the others are unchanged.

Number of bonds = number of central atoms bound to atoms.

Find the number of lone electron logarithms first.

Anion: a = the number of electrons in the outermost shell of the central atom + the number of charges.

Cation: a = the number of electrons in the outermost shell of the central atom - the number of charges, then the number of lone electron pairs = 1 2 (a-xb), and finally the number of bonds of the central atom.

For example: co -a = 1 2 (4 + 2-3 2) = 0 & the number of bonds is 3, so the number of valence shell electron pairs is 0 + 3 = 3

The number of valence shell electron pairs of the central atom (note that it is not the number of valence electrons) = the number of lone electron pairs of the central atom + the number of electron pairs of the central atom forming bonds with the surrounding atoms.

1. Find the central atom first, generally the valency value is larger, the bound atom is more, and the electronegativity is less (except for H).

2. Look at which main group the central atom is in, and the group number is the number of outermost electrons.

3. Then look at the number of electrons required by the atom that binds to the central atom (8-its group number).

4. The number of outermost electrons of the central atom minus the total number of electrons required by the surrounding atoms, and then divided by 2 is the number of lone electron pairs of the central atom.

5. Count how many atoms are combined with the central atom around the number, and the number of electron pairs between the central atom and the surrounding atoms is the number.

Let's take Co as an example, first determine that the central atom is C, and then know that C is a group IVA element, and the outermost electron number of C atom is 4, minus the number of electrons required for two O atoms to bond (each O needs 8-6 = 2 electrons, and two O need a total of 2 2 = 4 electrons).

That is, 4-4=0, which means that the C atom does not have lone pairs, but needs 2 bonds to bind with two O's, the valence shell electron pairs of the C atom are 0+2=2, the central C atom is SP heteroeugeneous, and the VSEPR configuration and molecular configuration are linear.

Another example is HO, the central atom is O, O belongs to the VIA group, the outermost number of electrons is 6, minus the number of electrons required for two H (since the ground state H atom has only 1s energy level, one more electron can be stable) 6-2 1=4, the number of lone pairs of electrons of O is 4 2=2.

Coupled to form two bonds with two Hs, the number of valence shell electron pairs of O is 2+2=4. The central atom O is sp3 hybridized, the VSEPR configuration is tetrahedral, and the molecular configuration ignores the lone pair of electrons and is V-shaped.

It is the number of valence electrons. Because the valence shell electrons refer toNucleusOuter electrons can be formed by interacting with other atomsChemical bonds, with the elementsThe price of the bridge segmentThe electrons in question, also known as valence electrons. And valence electrons are the electrons outside the nucleus that are important for participating in chemical reactions.

Number of valence electron logs.

Bonding electrons to n solitary electrons guess the finger pair m. The number of atoms in which the bonding electron pair n is bonded to the central atom. Lone electron pair m = (number of valence electrons of the central atom - unpaired atoms bound to the central atom eBook and) 2.

The sum of the number of valence shell electrons of the central atom and the number of shared electrons provided by the ligand is the number of valence shell electron pairs of the central atom. The halogen atom and h atom donate 1 electron, and the atom of the oxygen group element does not donate electrons; As the central atom, the halogen atom is counted as donating 7 electrons.

Valence shell electron pairs refer to the electrons in the outer nucleus of an atom that can interact with other atoms to form chemical bonds, which are related to the valence of the element. Main family elements.

The valence electrons are the outermost electrons of the main group of element atoms, the transition elements.

The valence electrons are not only the outermost electrons, but also the second-to-last electrons of the sub-outer shell and some ear matching elements can also be valence electrons.

Valence shell electrons. Logarithmic, which refers to the number of lone pairs of electrons present in a molecule.

Valence shell electron pairs bond lone electron pairs, where: lone electron pairs 1 2 (central atom valence electrons.

Number of the central atom combined with the number of atoms x the number of the bound atom can also accept a few electrons), if it is an anion.

The number of valence electrons of the central atom + the number of charges. If it's cationic.

The number of valence electrons of the central atom - the number of charges, the others are unchanged. Number of bonds = number of central atoms bound to atoms.

What is valence shell electron pairs:

Valence shell electron pairs, which refers to the number of lone pairs of electrons present in a molecule. A method for quickly judging the configuration of molecules and ions, in which the valence electrons in the molecule take the middle pair (including the bonding electron pair n, and the lone electron pair m) due to mutual repulsion, and tend to move as far away from each other as possible to reduce the repulsion. Note if there are lone pairs of electrons present in the molecule.

As lone pairs of electrons are closer to the nucleus than bonding electron pairs.

It has a greater repulsion effect on adjacent bond-forming electron field rental pairs, so that the corresponding bond angle becomes smaller. Molecules or ions with the same number of valence electrons (i.e., the total number of electrons or the total number of valence electrons) and the same number of atoms have the same structural characteristics. Molecules or ions that conform to the principle of isoelectric deridge ridges are called isoelectrons.

Valence electronsLogarithmic: Refers to the presence in the moleculeLone pairs of electronsThe number of pairs.

Number of valence shell electron pairs = bond + number of lone electron pairs, where: number of lone electron pairs = 1 2 (number of valence electrons of the central atom - number of bound atoms of the central atom x number of bound atoms and how many electrons can be accepted by the bound atom), if it is anion.

The number of valence electrons of the central atom + the number of charges. If it's cationic.

The number of valence electrons of the central atom - the number of charges, the others are unchanged. Number of bonds = number of central atoms bound to atoms.

Number of valence electron logs.

Valence electron logarithm calculation: valence electron logarithm = bonding electron pair n + lone electron pair m; The number of atoms in which the bonding electron pair n is bonded to the central atom. Lone electron pair m = (number of valence electrons of the central atom - sum of the number of unpaired electrons of the atom bound to the central atom) 2;The cation subtracts the number of charged on the molecule The anion adds the number of charged on the molecule.

For ABM-type molecules (A is the central atom and B is the coordination atom), n = (the number of valence electrons of the central atom + the number of valence electrons provided by each coordination atom m) 2, the geometric distribution of valence electron pairs when the number of valence electron pairs is .

They are linear, planar triangles, and tetrahedra.

Configuration.

For ABM-type molecules, if the number of valence electrons is equal to the number of coordination atoms, the spatial configuration and hybrid orbitals of the molecule.

The spatial configuration is the same. If the number of valence electron pairs is not equal to the number of coordination atoms, the lone electron pairs of the central atom affect the spatial configuration of the molecule. Orbital hybridization of carbon-containing atoms.

way of judgment.

The above content reference:Encyclopedia of 100 commas – the number of valence electrons

Valence shell electrons. There are two ways to calculate logarithms:

1. The valence electrons guess the number of commas into bond electron pairsLone electron pairsm。

2. The number of atoms in which the bonding electron pair n is bonded to the central atom.

Lone electron pair m = (number of valence electrons of the central atom - sum of the number of unpaired electrons of the atom bound to the central atom) 2;Cation.

Subtract the charged number anion from the molecule.

Add the number of charges carried to the molecule.

Specific steps to infer molecular spatial configurations:

1. First determine the number of valence shell electron pairs of the central atom, and then determine the hybrid orbital.

spatial configuration.

n=2 straight.

n=3 planar triangle.

n=4 regular tetrahedron.

2. Determine the lone pair of electrons of the central atom.

Logarithmic, inferring the spatial configuration of molecules.

If the logarithm of lone electrons is 0, the spatial configuration of the molecule is the same as that of the hybrid orbital.

If the logarithm of lone electrons is not 0, the spatial structure of the molecule is different from that of the hybrid orbital.

There are two ways to calculate the number of valence shell electron pairs:

1. The number of valence electron pairs is bonded electron pair n lone electron pair m.

2. The number of atoms in which the bonding electron pair n is bonded to the central atom.

Lone electron pair m = (number of valence electrons of the center-missing atom - sum of unpaired electrons of the atom bound to the central atom) 2. The cation subtracts the number of charged ions from the molecule, and the anion adds the charged number of the charged spike chain on the molecule.

Electron Theory:

The theory of valence shell electron pair repulsion suggests that when the number of valence shell electron pairs is 2, they are arranged in a straight line in space, and the bond angle is 180 degrees. When the number of electron pairs in the valence shell is 3, they are arranged in a planar triangle in space, and the bond angle is 120 degrees.

When the number of electron pairs in the valence shell is 4, it is arranged in a regular tetrahedral shape in space, and the bond angle is 109°28. This is their ideal configuration, which contains lone electron pairs, also known as the VSEPR model.

The ideal configuration of a molecule or ion with a valence shell electron pair of 4, i.e., the VSEPR model, is a tetrahedral shape.

According to the valence shell electron pair theory, the three-dimensional structure of a molecule is the result of the mutual repulsion of the "valence shell electron pairs" of the central atom.

The central atom, i.e., the atom that is the center, is generally 1.