Covalent Bonds
Review Reactivity – Electron configuration – Stability Chemical bond Lewis dot symbol
Covalent bond Bond in which two valence electrons are shared by two atoms – Occurs with elements close to each other on the periodic table – Ex: H 2 O, NH 3 (ammonia), CH 4 (methane) – Between a nonmetal and a nonmetal
3 Types of Covalent Bonds Single Covalent Bond Double Covalent Bond Triple Covalent Bond
3 Pencil Demo for Single, Double and Triple Covent bonds Make as many observations as you can i.e. facial expressions, body position, muscles used, noises made, force or energy exerted, etc.
Single Covalent Bonds Each atom shares one pair of electrons Each atom shares 2 electrons Longest bond Weakest bond of the three H—H Lewis Structure
Double Covalent Bonds In a double bond, each atom shares two pairs of electrons Each atom shares 4 electrons Medium length bond Medium strength bond Lewis Structure O2O2
Triple Covalent Bond In a triple covalent bond, each atom shares three pairs of electrons Each atom shares 6 electrons The shortest bond The strongest bond Carbon, nitrogen, oxygen, and sulfur can form double and triple covalent bonds N2N2 Lewis Structure
Strength of Covalent Bond Several factors control bond strength —Number of shared electrons-the more electrons shared, greater the bond —Size of the atom —Bond length – the greater the bond length, the weaker the bond
Substance Molecule Two or more atoms chemically bonded together Compound Two or more elements chemically bonded together
Molecules Diatomic CO HCl
Memeorize Diatomic Elements – elements that exist as two H 2, O 2, N 2, Cl 2, Br 2, I 2, F 2 – HONClBrIF – Magnificent 7-don’t forget H
Molecules Polyatomic O3O3 H2OH2O NH 3 CO 2
Compound Molecular Compound HClCO H2OH2O NH 3 CO 2 Binary Molecular Compound
Covalent Molecule Properties Covalent molecular solids 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