0304 Valence Electrons And Bonding Individual

03.04 Valence Electrons and Bonding
Individual neutral atoms are rarely found in nature. The noble gases are the only elements that are found as single atoms more often than they are found in compounds.
Atoms are held together in compounds by electrostatic attraction between positive nuclei and negative electrons. This attraction holds atoms together in a chemical bond, a link between two atoms resulting from the mutual attraction of their nuclei for valence electrons. All chemical bonds involve valence electrons, but the bonds are classified by the way in which electrons are distributed within the bonds.
Ionic and Covalent Bonds
We will be studying two types of chemical bonds in this module: ionic bonds and covalent bonds.
Atoms can gain or lose electrons to become charged ions. They form ionic bonds, a chemical bond that results from electrostatic attraction between positive and negative ions. This means that in an ionic bond, electrons are given up by one atom and gained by another atom, and then those atoms are attracted to each other. covalent bond, electrons are shared between two atoms, neither atom completely gains or loses electrons.

Electronegativity and Bond Properties
Chemical bonds can range in strength and properties between completely ionic and completely covalent, depending on how strongly the atoms attract the electrons. The greater the difference in their electronegativity values, the more ionic the chemical bond between two atoms.
When two atoms have a large difference in electronegativity, the strength of their attraction for the electrons involved in the bond, the atom with the greater electronegativity is able to take the electrons from the other atom. The more electronegative atom is able to take the electrons, becoming a negative ion, leaving the other atom as a positive ion.
A polar covalent bond is a covalent bond where the atoms have an unequal attraction for the shared electrons. A polar bond has an uneven distribution of the charge, because the shared electrons spend more time around the atom with the higher electronegativity value. This uneven sharing makes one end of the bond, where electrons spend more of their time, slightly negative and the other end slightly positive in charge.
When both atoms have the same strength of attraction for the electrons in the chemical bond, the electrons are shared equally between both atoms. These bonds are called non-polar covalent bonds.
Bonds that have a difference in electronegativity ranging from 1.7 to 4.0 are ionic bonds. Any bond with an electronegativity difference of less than 1.7 is a covalent bond. A bond with an electronegativity difference between 1.7 and 0.3 is polar covalent, while a bond with a difference of less than 0.3 is non-polar covalent.
Why Bonding Occurs bonding is driven by potential energy.
If the amount of their potential energy will be lowered by the change, two atoms will bond together. Most atoms have a lower potential energy in naturally occurring chemical bonds than they do as individual atoms.