Covalent Bonding! Co = Together

The Octet Rule The octet rule says that all atoms want to have eight valence electrons, like the noble gases. The octet rule says that all atoms want to have eight valence electrons, like the noble gases. One way that atoms can follow the octet rule is by giving and taking electrons… ionic bonding One way that atoms can follow the octet rule is by giving and taking electrons… ionic bonding englishclub.com

Covalent bonding The other way that atoms can follow the octet rule is by covalent bonding. The other way that atoms can follow the octet rule is by covalent bonding. Co means together or sharing, so covalent bonding happens when atoms share electrons and stick together. Co means together or sharing, so covalent bonding happens when atoms share electrons and stick together. Ionic vs. Covalent bonding Ionic vs. Covalent bonding Ionic vs. Covalent bonding Ionic vs. Covalent bonding

When does covalent bonding happen? Well, let’s think about it… Well, let’s think about it… Ionic bonding—give and take—happened between way different, or unequal, atoms. Ionic bonding—give and take—happened between way different, or unequal, atoms. When does sharing (remember co?) usually happen? When does sharing (remember co?) usually happen? Between equals??? Between equals??? thenextweb.com

Which brings us back to… Remember electronegativity? The ability of an atom to attract electrons? So if atoms have similar electronegativities they end up sharing electrons instead of giving and taking

Some numbers to live by If two atoms have close to the same electronegativity, usually a difference between 0.0 and 0.4, they will form non-polar (equally sharing) covalent bonds. If two atoms have close to the same electronegativity, usually a difference between 0.0 and 0.4, they will form non-polar (equally sharing) covalent bonds. If two atoms have a medium difference in electronegativity, usually between 0.5 and 1.7, they will form polar (unequally sharing) covalent bonds. If two atoms have a medium difference in electronegativity, usually between 0.5 and 1.7, they will form polar (unequally sharing) covalent bonds. If two atoms have a large difference in electronegativity, usually over 1.7, they will form ionic bonds If two atoms have a large difference in electronegativity, usually over 1.7, they will form ionic bonds

PC, NPC, or Ionic For the following compounds, determine if the bonding is ionic, polar covalent, or non-polar covalent. For the following compounds, determine if the bonding is ionic, polar covalent, or non-polar covalent. CO CO MgCl 2 MgCl 2 CH 4 CH 4 BaO BaO SiO 2 SiO 2 CuF 2 CuF 2 O 2 O 2 H 2 O H 2 O CaBr 2 CaBr 2 NO NO NaOH NaOH Note: When a metal and non-metal bond, they form ionic bonds (No matter what)! When two nonmetals bond, they form covalent bonds (No matter what)! Two metals don’t bond, they form alloys

Methane is covalently bonded X’s are Hydrogen electrons vinstan.wikispaces.com

Water is covalently bonded antranik.org

When does covalent bonding happen? Between atoms of the same element (Diatomic molecules). H2 O2 Between non-metals H2O CH4 CCl4 Between non-metals in polyatomic ions PO4-3 CH3COO-1

What are the properties of covalent molecules? Usually liquids or gases Usually liquids or gases Low melting and boiling points Low melting and boiling points Insoluble or very low solubility in water (don’t dissolve well) Insoluble or very low solubility in water (don’t dissolve well) Do not conduct electricity in solution Do not conduct electricity in solution Have odor Have odor allaboutboats.blogspot.com dailyforex.com dreamstime.com

Ionic vs. covalent PropertyIonic (Think Salt) Covalent (Think gasoline) State (at room temp.) SolidLiquid or gas Melting and boiling points HighLow Soluble in waterYesNo, or low Conduct electricity when dissolved in water YesNo OdorNoYes

Vocabulary Warning!!! You may have noticed I started using the word molecule instead of compound. You may have noticed I started using the word molecule instead of compound. I wonder why? I wonder why? Just trying to confuse you? Just trying to confuse you? Trying to increase your vocabulary? Trying to increase your vocabulary? Compound: Two or more different ELEMENTS chemically bonded. Compound: Two or more different ELEMENTS chemically bonded. Formula unit: Ratio for ionically bonded elements. Formula unit: Ratio for ionically bonded elements. Molecule: Two or more ATOMS covalently bonded. Molecule: Two or more ATOMS covalently bonded. What’s this mean for you? What’s this mean for you? All covalently bonded chemicals are molecules. All covalently bonded chemicals are molecules.

Compound, Molecule or Both? H 2 O H 2 O Covalent, so molecule Covalent, so molecule Two different types of atoms, so compound Two different types of atoms, so compound NaCl NaCl Ionic, so compound Ionic, so compound H 2 H 2 Covalent, so molecule Covalent, so molecule

More Compound, Molecule, or Both? CF4 Covalent, so molecule Two different types of atoms, so compound C2H5OH Covalent, so molecule Two different types of atoms, so compound MgCl2 Ionic, so compound

Back to covalent bonding In covalent bonding, the atoms can share 2 (1 pair), 4 (2 pair) or even 6 (3 pair) electrons!!! In covalent bonding, the atoms can share 2 (1 pair), 4 (2 pair) or even 6 (3 pair) electrons!!! Single bond: One shared pair of electrons Single bond: One shared pair of electrons Double bond: Two shared pairs Double bond: Two shared pairs Triple bond: Three shared pairs Triple bond: Three shared pairs N 2 N 2 Double and triple bonds form when an atom needs to share additional electron pairs to become like a noble gas Double and triple bonds form when an atom needs to share additional electron pairs to become like a noble gas Triple bonds are the strongest and the shortest Triple bonds are the strongest and the shortest en.wikipedia.org