Molecular Bonds
Molecular Bonds
When atoms do not have a complete octet, the valance electrons of the atoms can react with other atoms valance electrons. The interactions that occur when the atoms are close together are held by attractions called chemical bonds. A covalent bond is formed when two atoms share a pair of valance electrons. Covalent bonds are normally formed by a non-metal bonding to another non-metal. Two or more atoms held together by covalent bonds are a molecule. When drawing a structural formula to show the number and type of bonds you will use a line to show a single bond ,one pair of shared electrons, and two lines to show a double covalent bond or two pairs of shared valance electrons. An atoms bonding limit, it's valance, is equal to the number of unpaired electrons in the valance shell. Covalent bonds can also form pure elements by bonding atoms of the same element and compounds by bonding atoms of different elements. The attraction of an atom for the shared electrons of a covalent bond is called it's electronegativity. When a covalent bond shares the electron pairs equally then it is called a non-polar covalent bond and if the electron pairs are share unequally then it is called a polar covalent bond. An ionic bond will form when toe atoms are very unequal in their electronegativity and so one atom will steal the electrons from the other. After the ionic bond occurs both atoms are no longer neutral and have charges therefore they are called ions. Atoms then that have positive charges are called cations and atoms with negative charges are called anions. Cations and anions generally will form ionic bonds. Compounds that are formed by ionic bonds are called ionic compounds and generally result in salts. Hydrogen bonds are formed when a hydrogen atom that is already covalently bonded to one electronegative atom and is attracted to another electronegative atom. Atoms can also have fleeting reactions called Van Der Waals Interactions, this is what allows a gecko to stick to a wall.