Objective: To introduce molecular compounds and practice covalent compounds Do Now: Name the chemical compounds and write the formulas for the following: Lithium and Fluorine Iron (III) and Phosphorus

Molecular Compounds You learned in Chapter 7 two types of bonding Ionic – between a metal and a nonmetal Typically metal loses, nonmetals gain electrons Metallic- between 2 or more metals by “sea of electrons” Covalent bonding: when two or more nonmetals share electrons to reach octet

Molecular Compounds Molecule: neutral group of atoms joined together by covalent bonds Examples: water, ozone, sugar Diatomic molecule: molecule that contains two of the same atoms Hydrogen, nitrogen, oxygen, and the halogens (naturally found in nature as a diatomic)

Molecular formula: chemical formula for molecular compounds Shows how many atoms of each element a substance contains H2O = 2 hydrogen atoms, and 1 oxygen atom

Try these out How many of each atoms are in the following molecular compound Butane C 4 H 10 Ethanol C 2 H 6 O Nitrous Oxide N 2 O

Comparing Ionic and Molecular Compounds Molecular Representative unit is a molecule Composed of two or more nonmetals Tend to have lower melting and boiling points Many are gases and liquid at room temperature Ionic Representative unit is a formula unit Composed of cations and anions High melting and boiling points Many are crystals at room temperatures

Octet Rule for Covalent Bonding Rather than losing or gaining electrons, these nonmetals will share electrons to hit octet 2 electrons share for every covalent bond H. + H. H:H or H H :F:+ :F::F:F: or :F F:.....

Octet Rule Structural formulas determine the covalent bonds by dashes H- H In fluorine molecule (F 2 ) the unshared pair are represented by (..) also known as lone pair or unshared pair of the electrons Example: Water (H 2 O)

Double and Triple Bonds Molecules can share more than one pair of electrons to reach octet Triple Bond H – C = C – H Double bond H – C = C - H H H

Naming Molecular Compounds

Just like ionic compounds, you list the element that is shown first, to the last. With molecular compounds, use prefixes to determine how many of each element is present (if there is one present in the first element shown, no prefixes) Last element will end in –ide Diphosphorus trioxide (P 2 O 3 ) Sulfur trioxide (SO 3 )

Naming Molecular Compounds Prefix Mono Di Tri Tetra Penta Hexa Hepta Octa Nona deca Number

Example NCl 3 H 2 S N 2 O 3 SiCl 4