1. Nomenclature and Covalent Bonding

2. Covalent bonds Covalent (co—sharing; valent—outermost shell) when electrons are shared between 2 nuclei Molecule- a group of atoms held together by covalent bonds In covalent bonding, the atoms are able to achieve an octet through the sharing of electrons

3. Molecules Are held together by the attraction of electrons of one atom and the nucleus of a second atom Their bonds are flexible, somewhat like springs A single bond forms from a single pair of shared electrons Br Br-Br

4. Double Bond 2 PAIRS of shared electrons form a double bond This is 1 DOUBLE BOND OO C

5. Triple Bond So, what would a triple bond look like? Each line represents 1 shared PAIR of electrons Is there something unusual here ?

6. Covalent Compound Properties Lower melting and boiling points vs. ionic Molecules have no charge, hence do not conduct heat or electricity in any state. Melting molecular compounds Does NOT separate the clusters of atoms within a molecule, Separates just molecules from each other

7. Naming Binary Covalent compounds Molecular compound (Covalent compounds) names include prefixes that indicate the number of atoms in the molecule They are composed of nonmetal elements

8. Naming Binary Covalent compounds Write the name of the least electronegative element with a prefix to indicate the number of atoms of the element that are present Prefix mono- is NOT written with the first word of a covalent compound’s name

10. Number of atoms PrefixNumber of atoms Prefix 1Mono-6Hexa- 2Di-7Hepta- 3Tri-8Octa- 4Tetra-9Nona- 5Penta-10Deca- Some prefixes are sometimes shortened to make a name easier to say (aka: you may have to remove the “a”)

11. Naming Binary Covalent Compounds Write the name of the most electronegative element second with a prefix to indicate the number of atoms of the element that are present

12. Number of atoms PrefixNumber of atoms Prefix 1Mono-6Hexa- 2Di-7Hepta- 3Tri-8Octa- 4Tetra-9Nona- 5Penta-10Deca- Some prefixes are sometimes shortened to make a name easier to say (aka: you may have to remove the “a”)

13. Naming covalent compounds Suffix –ide is added to the name of the last element H 2 O is dihydrogen monoxide NH 3 N2H4N2H4 phosphorus pentachloride nitrogen monoxide carbon tetrachloride

14. Diatomic Elements A diatomic molecule is a molecule formed from two identical atoms The atoms join together because they are more stable that way than if they exist as single atoms Remember H. Br O N Cl I F H 2, Br 2, O 2, N 2, Cl 2, I 2, F 2