Structural expressions of organic compounds: spider web form, abbreviation form, bond line form

Spatial arrangement of atoms: baseball model, scale model, wedge model

Reasons for the large number of organic compounds: 1. Isomerism 2. The fourth main group of the second cycle of carbon element can form chemical bonds with H, O, S halogens

Characteristics of organic matter: 1. Low melting and boiling point 2. Easy to burn 3. Hardly soluble in water, easily soluble in organic solvents 4. Slow reaction speed, multiple side reactions

Lewis's classic covalent theory: Atoms of the same element or elements with similar electronegativities can form molecules by sharing electron pairs. The chemical bond formed by sharing electron pairs is called a covalent bond.

Octet: Each atom has an outer electron configuration of 8️⃣ electrons of a stable noble gas atom (he is 2 electrons)

Basic points 1. The principle of electron pairing and bonding determines that covalent bonds are saturated. 2. The principle of maximum orbital overlap determines that covalent bonds have directionality. 3. Symmetry matching, that is, atomic orbitals will only overlap when they have the same sign.

Types of covalent bonds: σ bond and π bond

Basic points 1. The same atoms have similar energy composition 2. The number of orbitals remains the same but the energy shape and space extension direction are different 3. The bonding ability becomes stronger

Type: sp (sp1, sp2, sp3), spd

Sub-primary bond length: the internuclear distance of the bonding atoms (determines the spatial configuration of the molecule) Bond angle: the angle between two covalent bonds (determines the spatial configuration of the molecule) Bond energy: dissociation energy or average dissociation energy → chemical bond strength The polarity of the bond: the charge distribution between the bonding atoms → affects the physical and chemical properties

non-polar

polarity

Another classification

Dipole-dipole force

hydrogen bond

According to different carbon frame

Homolysis (reactions that produce active atoms or atomic groups with unshared electrons are called free radicals are called free radical reactions) and heterolysis

subtopic

Lewis acid is a substance that can accept a pair of electrons to form a covalent bond; Lewis base is a substance that can donate a pair of electrons to form a covalent bond. Acids are electron pair acceptors; bases are electron pair donors.

The essence of acid-base reaction is the process of forming coordination bonds to obtain an acid-base adduct.

Chemical bonds are produced by overlapping atomic orbitals. Any number of overlapping atomic orbitals can form the same number of molecular orbitals, such as the formation of H₂

Only when the molecule is in an excited state does the antibonding orbital have electrons

Among the molecular orbitals generated by the combination, those with energy lower than the atomic orbitals are called bonding orbitals; those with energy higher than the atomic orbitals are called antibonding orbitals.

The basic content of resonance theory: A molecule or ion can be represented by ≥ 2 Lewis structural formulas with different electron positions. In resonance theory, each Lewis structural formula is called a resonance formula. Any single resonance formula cannot represent the real structure of a molecule or ion. Only a group of resonance formulas or a resonance hybrid can represent the structure of a molecule or ion. real structure.