covalent character
(noun)
The partial sharing of electrons between atoms that have an ionic bond.
Examples of covalent character in the following topics:
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Ionic vs Covalent Bond Character
- All bonding interactions have some covalent character because the electron density remains shared between the atoms.
- The degree of ionic versus covalent character of a bond is determined by the difference in electronegativity between the constituent atoms.
- Bonds that fall in between the two extremes, having both ionic and covalent character, are classified as polar covalent bonds.
- Though ionic and covalent character represent points along a continuum, these designations are frequently useful in understanding and comparing the macroscopic properties of ionic and covalent compounds.
- This bond is considered to have characteristics of both covalent and ionic bonds.
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Types of Bonds
- Pure ionic bonding cannot exist: all ionic compounds have some degree of covalent bonding.
- Thus, an ionic bond is considered a bond where the ionic character is greater than the covalent character.
- Bonds with partially ionic and partially covalent character are called polar covalent bonds.
- A covalent bond involves electrons being shared between atoms.
- This difference in charge is called a dipole, and when the covalent bond results in this difference in charge, the bond is called a polar covalent bond.
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Salt Formation
- In the case of alkali metal hydroxides and simple amines (or ammonia) the resulting salts have pronounced ionic character and are usually soluble in water.
- Heavy metals such as silver, mercury and lead form salts having more covalent character (3rd example), and the water solubility is reduced, especially for acids composed of four or more carbon atoms.
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Ionic Bonding and Electron Transfer
- Ionic bonds differ from covalent bonds.
- However, in covalent bonds, the electrons are shared between the two atoms.
- All ionic bonds have some covalent character, but the larger the difference in electronegativity between the two atoms, the greater the ionic character of the interaction.
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Explanation of Valence Bond Theory
- Valence bond theory states that overlap between two atomic orbitals forms a covalent bond between two atoms.
- According to VB theory, a covalent bond forms from the physical overlap of half-filled valence orbitals in two atoms.
- The VB theory describes the formation of covalent bonds from the overlap of atomic orbitals on two different atoms.
- This theory is used to explain the covalent bond formation in many molecules.
- Mutual sharing of electrons between H and F results in a covalent bond in HF.
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Halogenation
- Since only two covalent bonds are broken (C-H & Cl-Cl) and two covalent bonds are formed (C-Cl & H-Cl), this reaction seems to be an ideal case for mechanistic investigation and speculation.
- The covalent bond homolyses that define the bond dissociation energies listed above may are described by the general equation:
- However, this reasoning fails to recognize that covalent bonds between different atoms or groups may experience additional stabilization as a result of ionic character.
- Resonance theory explains this additional bonding energy by a significant ionic character (ca. 20%) of the covalent bond.
- The ionic character of a single covalent bond increases with the electronegativity difference between the bonded atoms.
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Binary Hydrides
- Instead, many compounds have a hydrogen center with a hydridic character.
- Hydrides can be characterized as ionic, covalent, or interstitial hydrides based on their bonding types.
- Covalent hydrides refer to hydrogen centers that react as hydrides, or those that are nucleophilic.
- In these substances, the hydride bond, formally, is a covalent bond much like the bond that is made by a proton in a weak acid.
- Transition metal hydrides also include compounds that can be classified as covalent hydrides.
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Bond Polarity
- Molecular polarity is dependent on the presence of polar covalent bonds and the molecule's three-dimensional structure.
- Bond polarity: when atoms from different elements are covalently bonded, the shared pair of electrons will be attracted more strongly to the atom with the higher electronegativity.
- Such bonds are said to be 'polar' and possess partial ionic character.
- Molecular polarity: when an entire molecule, which can be made out of several covalent bonds, has a net polarity, with one end having a higher concentration of negative charge and another end having a surplus of positive charge.
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Percent Ionic Character and Bond Angle
- Chemical bonds are more varied than terminology might suggest; they exist on a spectrum between purely ionic and purely covalent bonds.
- The electron-pair bond is clearly responsible for this situation; this provides the covalent bond's stability.
- Think of this skewing's magnitude as the percent ionic character of a bond; to determine the percent ionic character, one must look at the electronegativities of the atoms involved and determine how effective the electron sharing is between the species.
- The more ionic character there is to a bond, the more likely that non-directional electrostatic interactions are holding the atoms together.
- Does this make an ionic bond, a covalent bond, or something in between?
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Atomic and Molecular Orbitals
- A more detailed model of covalent bonding requires a consideration of valence shell atomic orbitals.
- The bonding MO is occupied by two electrons of opposite spin, the result being a covalent bond.
- In the case of bonds between second period elements, p-orbitals or hybrid atomic orbitals having p-orbital character are used to form molecular orbitals.
- Thus, pi-bonding is generally found only as a component of double and triple covalent bonds.
- Here, the correlation diagram correctly accounts for the paramagnetic character of this simple diatomic compound.