How to determine the number of bonding pairs between electronically interatomic atoms

An element into the key branch hall socks covered with how muchThe number of outermost electronsRelate.

For example, phosphorus has 5 electrons in its outermost shell, so phosphorus atoms can form up to 5 single bonds.

But this is only the most formed strong hidden bond, and the phosphorus atom can also form 3 bonds (such as pH3), so it is shown that phosphorus has two valences.

There are two types of 3 and +5 prices.

The number of lone electron logs is calculated by the number of lone electrons = 1 2 * (a-xb). Lone electrons refer to nonbonding electrons that are not used to form covalent bonds in the outermost electron shell of the atom in addition to the bonded electrons used to form covalent bonds. These unbonded pairs of valence electrons are called lone electrons.

<> where a is the number of valence electrons of the central atom, x is the number of atoms bound to the central atom, and b is the maximum number of electrons that the atom bound to the central protozoa can accept. For example, the central atom of Hzo is oxygen, a is the outermost electron number of oxygen 6, x is the number of paired atoms 2, b is the number of paired atoms and the number of electrons that can be accommodated is 1.

According to the calculation formula, 1 2* (6-2 1) = 2, and the number of empty sensitive logs of solitary matter is 2.

Lone pairs refer to the fact that in addition to the bonded electrons used to form covalent bonds, there are often nonbonding electrons in the outermost electron shell of the atom that are not used to form covalent bonds. These unbonded pairs of valence electrons are called lone pairs. "Lonely" because it is not bonded, while "Pair" is because two electrons with opposite spins will pair.

Lone pairs are pairs of electrons that molecules or ions do not share a valence shell. The presence and distribution of lone pairs of electrons in the molecule affect the shape, dipole moment, bond length, bond energy, etc., especially on the molecule composed of light atoms. The alkalinity of Lewis bases, the bonding of ligands to centrosomes by coordination atoms, and the occurrence of nucleophilic reactions are all through lone pairs.

You can see from the law of covalent bond formation:

A single key is a key;

Double bonds are one key, one key, three bonds, one key, two keys.

So you can determine how many bonds and how many bonds exist between atoms based on the number of covalent bonds in a molecule.

For example: there are four carbon-hydrogen single bonds and one carbon-carbon double bond in an ethylene molecule, so there are 5 bonds and one bond in an ethylene molecule.

Coordination number, in coordination chemistry, refers to the number of coordination atoms around the central atom in a compound.

It should be the number of valence electrons provided by the coordination atom, right?

Did you see it there in the calculation of VSEPR or what.

In molecular orbital theory, the bond order refers to half of the number of net bonded electrons, and how the electrons are arranged in the orbital according to the three principles of electronic arrangement: that is, the principle of lowest energy, etc. For example, for O2+(15E), the molecular orbital arrangement is:

1s)2 (σ1s)2 (σ2s)2 (σ2s)2 (σ2px)2 (π2py)2 (π2pz)2 (π2py)1

The key level is: 1 2 [ 2+2+2+2+2)- 2+2+1)] = , and the key level is.

In the same way, the o and o - bond levels are 2 and , respectively.

where the anti-key orbital is denoted by a "*".

Memorize the molecular orbital energy level diagram in the book.

When doing the problem, the bonding electrons are filled into the molecular orbitals in order from low to high, first single and then in pairs.

Then you can determine the number of bonded electrons and the number of antibonded electrons.

If you want to cause this factor, I think it's better to be cheap e-books.

Number of electron pairs = (number of valence electrons of the central atom + number of bonding atoms - number of charges) 2 Number of bonding atoms excluding o.

e.g. coCl2 = (4 + 2) 2 = 3SO4(2-) = [6 + 0 - 2) ] 2 = 4[pcl6](-= [ 5 + 6 - 1)] 2 = 6xeof4 = (8 + 4) 2 = 6