Covalent Compounds

Bonds… Covalent Bonds. Electrons jump from one atom to another in Ionic Bonds But, in covalent bonds, the atoms share electrons between one another.

Another reminder about electrons… Check combining powers of elements in order to know how many they will share. 1 2 3 4 2 1 3 Nonmetals gain electrons & become - Metals lose electrons & become +

Covalent Bonds—Sharing Some atoms are unlikely to lose or gain electrons because the number of electrons in their outer levels makes this difficult. They have a tight hold on their electrons; they are very electronegative. If they won’t give up an electron, they share them, instead!

The Covalent Bond The chemical bond that forms between nonmetal atoms when they share electrons is called a covalent bond.

The Covalent Bond Shared electrons are attracted to the nuclei of both atoms. They move back and forth between the outer energy levels of each atom in the covalent bond. So, each atom has a stable outer energy level some of the time.

Here’s what we mean:

The Covalent Bond The neutral particle is formed when atoms share electrons is called a molecule A molecule is the basic unit of a molecular compound.

Some examples of covalent bonds: Molecular compounds involve two non-metals. They have low melting points, aren’t as soluble in water, & are poor conductors of heat or electricity.

More examples of covalent bonds:

The Polar Covalent Bond Special case of uneven sharing; water is a polar covalent substance, due to Oxygen. I can haz covalent bond?

Covalent compounds: Formulae Both elements are nonmetals, so put the less electronegative one first. (the one further left on the periodic table!) Check the combining powers for each element, and swap them. E.g., H = 1, O = 2  H2O

Covalent compounds: Formulae Examples Carbon + one oxygen = CO Carbon + two oxygens = CO2 Silicon + Bromine? Arsenic + Fluorine Nitrogen + Iodine Hydrogen + Sulfur? SiBr4 AsF3 NI3 H2S

Covalent compounds: Names Just like the formulae, write the less electronegative one first. (the one further left on the periodic table!) Change the more electronegative one’s (i.e., the second one’s) name to end in -ide Include prefixes to indicate number of atoms, based on the combining powers.

Covalent compounds: Name Examples Carbon + one oxygen = Carbon monoxide Carbon + two oxygens = Carbon dioxide Silicon + Bromine? Arsenic + Fluorine Nitrogen + Iodine Hydrogen + Sulfur? Silicon tetrabromide Arsenic trifluoride Nitrogen triiodide dihydrogen sulfide