Covalent Bonds

Why do atoms bond? Atoms want STABILITY- to achieve a noble gas configuration (octet) For ionic bonds there is a transfer of electrons to get an octet of electrons For covalent bonds there is a sharing of electrons to get an octet

What is a covalent bond? Covalent bond - the chemical bond that results from sharing of valence electrons Occurs with elements close to each other on the periodic table Between a nonmetal and a nonmetal Molecule is two or more atoms bonded covalently

Examples of Molecules F2 H2O NH3 (ammonia) CH4 (methane) Notice there are no metals, only non-metals

Diatomic Molecules Some atoms do not exist as a single atom Atoms that exist as two H2, O2, N2, Cl2, Br2, I2, F2 HONClBrIF Magnificent 7-don’t forget H

3 Types of Covalent Bonds: Single, Double and Triple bonds

Strength of Covalent Bond Several factors control bond strength Number of shared electrons-the more electrons shared, the shorter the bond, the greater the bond strength Size of the atoms

Single Covalent Bonds Each atom shares one pair (2 total) of electrons Longest bond Weakest bond of the three

Double Covalent Bonds Each atom shares two pairs (4 total) of electrons Medium length bond Medium strength bond

Triple Covalent Bond Each atom shares three pairs (total 6) of electrons Shortest bond Strongest bond Carbon and nitrogen can form triple covalent bonds

Single, Double & Triple Bonds

Covalent Molecule Properties Tend to be soft solids, liquids, or gases at room temperature Low melting and boiling points Poor conductors of heat and electricity Non-electrolytes – do not conduct electricity in water