Module 2 INORGANIC CHEMISTRY 2

Polar Covalent Bond

A bond between 2 nonmetal atoms that have different electronegativities and therefore have unequal sharing of the bonding electron pair Example: In H-Cl, the electronegativity of the Cl atom is 3.0, while that of the H atom is 2.1 The result is a bond where the electron pair is displaced toward the more electronegative atom. This atom then obtains a partial-negative charge while the less electronegative atom has a partial-positive charge.This separation of charge or bond dipole can be illustrated using an arrow with the arrowhead directed toward the more electronegative atom. The Greek letter delta indicates "partially". Within a molecule each polar bond has a bond dipole A polar molecule always contains polar bonds, but some molecules with polar bonds are nonpolar.

Non Polar Covalent Bond

A bond between 2 nonmetal atoms that have the same electronegativity and therefore have equal sharing of the bonding electron pair Example: In H-H each H atom has an electronegativity value of 2.1, therefore the covalent bond between them is considered nonpolar

Covalent Bonding

A covalent bond, also called a molecular bond, is a chemical bond that involves the sharing of electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs, and the stable balance of attractive and repulsive forces between atoms, when they share electrons, is known as covalent bonding.

Double Covalent Bond

A double covalent bond is where two pairs of electrons are shared between the atoms rather than just one pair. Two oxygen atoms can both achieve stable structures by sharing two pairs of electrons as in the diagram.

Hydrogen Bond

A hydrogen bond is a weak type of force that forms a special type of dipole-dipole attraction which occurs when a hydrogen atom bonded to a strongly electronegative atom exists in the vicinity of another electronegative atom with a lone pair of electrons. These bonds are generally stronger than ordinary dipole-dipole and dispersion forces, but weaker than true covalent and ionic bonds.

Triple Covalent Bond

A triple bond in chemistry is a chemical bond between two atoms involving six bonding electrons instead of the usual two in a covalent single bond. The most common triple bond, that between two carbon atoms, can be found in alkynes.

Inert/Noble Gasses

At the top of the noble gases is little helium (He), with a shell that is full with only two electrons. The fact that their outer shells are full means they are quite happy and don't need to react with other elements. In fact, they rarely combine with other elements. The noble gases are the chemical elements in group 18 of the periodic table. They are the most stable due to having the maximum number of valence electrons their outer shell can hold. Therefore, they rarely react with other elements since they are already stable.

Covalent Bonding - How They Form

Covalent bonding occurs when pairs of electrons are shared by atoms. Atoms will covalently bond with other atoms in order to gain more stability, which is gained by forming a full electron shell. By sharing their outer most (valence) electrons, atoms can fill up their outer electron shell and gain stability.

Hydrogen Bonds - How they Form

How are they formed? a hydrogen bond is formed when a charged part of a molecule having polar covalent bonds forms an electrostatic (charge, as in positive attracted to negative) interaction with a substance of opposite charge. Molecules that have nonpolar covalent bonds donot form hydrogen bonds.

Ionic Bonding

Ionic bonding is the complete transfer of valence electron(s) between atoms and is a type of chemical bond that generates two oppositely charged ions. It is observed because metals with few electrons in its outer-most orbital. Ionic bonds are atomic bonds created by the attraction of two differently charged ions. The bond is typically between a metal and a non-metal. The structure of the bond is rigid, strong and often crystalline and solid. Ionic bonds also melt at high temperatures. Dissolved in water, ionic bonds are aqueous, that is they can conduct. As solids they are insulators. Ionic bonds can also be called electrovalent.

Ionic Bonding - How they Form

Ionic bonding is the complete transfer of valence electron(s) between atoms. It is a type of chemical bond that generates two oppositely charged ions. In ionic bonds, the metal loses electrons to become a positively charged cation, whereas the nonmetal accepts those electrons to become a negatively charged anion

Cations & Anions

Positive and Negative Ions: Cations and Anions. Cations (positively-charged ions) and anions (negatively-charged ions) are formed when a metal loses electrons, and a nonmetal gains those electrons.

Ionic Bond Examples

LiCl - Lithium Chloride LiBr - Lithium Bromide LiI - Lithium Iodide NaF - Sodium Fluoride NaCl - Sodium Chloride NaBr - Sodium Bromide NaI - Sodium Iodide KF - Potassium Fluoride KCl - Potassium Chloride KBr - Potassium Bromide KI - Potassium Iodide CsF - Cesium Fluoride CsCl - Cesium Chloride CsBr - Cesium Bromide CsI - Cesium Iodide BeO - Beryllium Oxide

Examples of Non Polar & Polar Covalent Bonds

Non-Polar Bonds Any bond between two identical atoms is non-polar since the electronegativities of the two atoms is identical. The simplest examples are the diatomic molecules such as H2, N2, and F2. The C-C bond in ethane, H3C-CH3, is also non-polar. Polar Bonds Any bond between two non-identical atoms is polar. The bond in HF is polar. So are the C-H bonds in CH4. Both C-C bonds in propane CH3CH2CH3 are polar. This is because the terminal carbon atoms and the central carbon are not identical. The terminal carbon atoms are both bonded to three hydrogen atoms and the central carbon atom. The central carbon, however, is bonded to two hydrogen atoms and two carbon atoms. An alternative way to think about this is to identify the groups that are attached to each carbon in propane. The left-hand carbon is attached to three hydrogen atoms and a CH2CH3 (ethyl) group. The central carbon is attached to two hydrogen atoms and two CH3 (methyl) groups. Since the right-hand carbon is attached to three hydrogen atoms and an ethyl group, it is identical to the left-hand carbon. Looking at propane in this way allows us to introduce the idea of group electronegativities

Covalent Bonds Examples

PCl3 CH3CH2OH O3 - ozone H2 - hydrogen H2O - water HCl - hydrogen chloride CH4 - methane Covalent compounds also are known as molecular compounds. Organic compounds, such as carbohydrates, lipids, proteins and nucleic acids, are all examples of molecular compounds. You can recognize these compounds because they consist of nonmetals bonded to each other.

Hydrogen Bond Examples

Usually, hydrogen bonds occur between hydrogen and fluorine, oxygen, or nitrogen. Sometimes the bonding is intramolecular, or between atoms of a molecule, rather than between atoms of separate molecules. Here is a list of other molecules that exhibit hydrogen bonding: chloroform - CHCl3 - between hydrogen of one molecule and carbon of another molecule ammonia - NH3 - between hydrogen of one molecule and nitrogen of another acetylacetone - C5H8O2 - intramolecular hydrogen bonding between hydrogen and oxygen DNA - hydrogen bonding between base pairs nylon - hydrogen bonds between the repeating units of the polymer