Covalent Bonding by: Braelyn Gilman

Melting and Boiling Points of Molecular and Ionic compounds  Ionic compounds are the strongest, breaking the bonds takes immense amounts of energy, boiling and melting points extremely high. Ionic compounds do not conduct electricity.  Molecular compounds have no bonds to break so the melting and boiling points are low.

The Molecular Formula  The molecular formula specifies the actual number of atoms of each element in a molecule  For example, the molecular formula for water, H2O, specifies that there are two hydrogen atoms and one oxygen atom present in each molecule of water.

Result of Electrons Sharing in Covalent Bonds  It helps an atom to contain a full shell part of the time. They share ions to make the shell complete and to make them happy.  For example if me and Tiffany each had seven electrons but she lost one and I had an extra I would share with her and it would keep our shells to make us happy.

Electron dot structures and shared electrons  Electron dot structure - valence electrons are represented by dots placed around the chemical symbol. Electrons are placed two on each side of the elemental symbol for a maximum of eight, which is the number of electrons in a filled S and P shell.  Electron dot structure - valence electrons are represented by dots placed around the chemical symbol. Electrons are placed two on each side of the elemental symbol for a maximum of eight, which is the number of electrons in a filled S and P shell.  Period one (hydrogen and helium) represents an exception where only a maximum of two electrons are placed on one side of the element.  Electron dot structures for the first two periods - Number of valence electrons related to group number

Atoms forming double or triple covalent bonds  Covalent bonds: formed from sharing of two electrons. Sharing electrons is one way that atoms can satisfy the "Octet Rule" atoms, by sharing electrons to form an electron-pair bond, can acquire a stable, noble-gas structure". There are 3 kinds of covalent bonds based on number of pairs of electrons shared between the two atoms:  single covalent bond - 1 shared pair  double covalent bond - 2 shared pairs  triple covalent bond - 3 shared pairs  Bond energy: single < double < triple Bond length: single < double < triple

The strength of a covalent bond and bond dissociation energy  They are related by the energy needed to break one molded bond.  A large bond disassociation energy corresponds to strong covalent bonds they are unreactive partly because the disassociation for each of these bonds are high

Oxygen atoms bonded in ozone  The chemical formula for ozone is O3 - three oxygen atoms.  The ozone is created when oxygen collides with atoms of oxygen producing Oxygen

Some exceptions to the octet rule  There are two ways that atoms will not be able to obey the octet rule. These are:  1. Having too few valence electrons to ever obtain an octet. 2. Expanding the octet to have 10, 12 or 14 valence electrons instead of 8.

Atomic and molecular orbitals relations  A molecular orbital is a mathematical function describing the wave-like behavior of an electron in a molecule. Molecular orbitals are further divided according to the types of atomic orbitals

The VSEPR theory helps predict the shapes of molecules  Valence shell electron pair repulsion (VSEPR) theory is a model in chemistry used to predict the shape of individual molecules based upon the extent of electron-pair electrostatic repulsion.