Chemical Bonding and Nomenclature Chemical Bonding and Nomenclature

s 8 I want you to meet a friend of mine? Bonding, the way atoms are attracted to each other to form molecules, determines nearly all of the chemical properties we see. And, as we know, the number “8” is very important to chemical bonding.

What are Molecules? What are Molecules? Molecules are a combination of atoms bonded together (compounds) Bonding determines the chemical properties of the molecule (compound).

3 Kinds of Chemical Bonds IONICCOVALENTMETALLIC

Ionic Bonds -Being Like the Noble Gases All atoms want to have the same number of electrons as the Noble Gases. The Noble Gases have very stable electron configurations. Metals- positive charge + lose electrons & become cations Non-Metals- negative charge - gain electrons & become anions N becomes N -3 Al becomes Al +3 Cl becomes Cl - O becomes O -2 Mg becomes Mg +2 Na becomes Na + The positive and negative ions are attracted to each other electrostatically. Ionic – Bonding because opposite ions attract

Opposites Attract! george-zaidan-and-charles-morton

How do we know how many atoms of each in an ionic bond? You did this yesterday Ioinic Compounds are stable – NEUTRAL Negative charge must equal the positive charge Let’s Use the Criss-Cross Method!

Putting Ions Together To get equal cations and anions in an ionic compound, you need to show how many of each Ca +2 & F -1 Now I know we will need two F ions to match the Ca ion CaF 2 Subscripts: The number that tells how many atoms/ions are in the formula

Ion Formulas To get equal cations and anions in an ionic compound, you need to show how many of each Ca +2 & F -1 criss-cross: Now I know we will need two F ions to match the Ca ion writtten like this: CaF 2 Subscripts: The number that tells how many atoms / ions are in the formula

Ion Formulas Remember those polyatomic ions (poly-many atomic-atoms) They stay whole in compounds, need more than one, must do so for whole ion: Ca +2 & PO 4 -3 cc: Written like this: Ca 3 (PO 4 ) 2

Putting Ions Together-Formulas Na + + Cl - = NaCl Na + + O -2 = Na 2 O Al +3 + S -2 = Al 2 S 3 Ca +2 + N -3 = Ca 3 N 2 You try these! Mg +2 + F - = NH PO 4 -3 =K + + Cl - = Li + + Br - =MgF 2 (NH 4 ) 3 PO 4 KCl LiBr

Practice Use Criss Cross Strategy Use Criss Cross Strategy You will need periodic table You will need periodic table

Naming Compounds Metal’s name goes first (cation)– do not change it except Iron = Ferrous Metal’s name goes first (cation)– do not change it except Iron = Ferrous Non-metal (anion) name is changed Non-metal (anion) name is changed End of original name taken off and replaced with “ide” oxygen = oxide nitrogen= nitride flourine= flouride End of original name taken off and replaced with “ide” oxygen = oxide nitrogen= nitride flourine= flouride REMEMBER Polyatomics stay as is, no name change REMEMBER Polyatomics stay as is, no name change

Naming Examples Al 2 S 3 Al 2 S 3 Aluminum and Sulfur Aluminum Sulfide Aluminum Sulfide Fe 2 O 3 Ferrous (Iron) and Oxygen Ferrous Oxide Ferrous Oxide

The Covalent Bond The Covalent Bond Atoms can form molecules by sharing electrons. Covalent Bonding – bonding by sharing electrons This is done only among non-metal atoms.

Covalent Bonds continued… Remember the Lewis Dot diagram- shows the valence electrons….helps us show how covalent bonds form

Let's Try it! Hydrogen and Oxygen 4 NB

Let's Try it! Hydrogen and Nitrogen

Let's Try it! Carbon and Oxygen

Naming compounds: covalent Element furthest on the left of the periodic table named first Element furthest on the left of the periodic table named first 2 nd element’s last letters replaced with –ide (example: chlorine -> chloride) 2 nd element’s last letters replaced with –ide (example: chlorine -> chloride) Use Greek prefixes for the number of atoms (mono, di, tri, tetra, penta, hexa, hepta, octa, nona, deca) Don’t use mono if only one atom of first element. Use Greek prefixes for the number of atoms (mono, di, tri, tetra, penta, hexa, hepta, octa, nona, deca) Don’t use mono if only one atom of first element.

Let’s Practice! Name the following. PH 3 CO HI N 2 O 3

Characteristics of Ionic compounds: At room temperature, most are crystals At room temperature, most are crystals Dissolve well in water, but NOT in a non- polar liquid Dissolve well in water, but NOT in a non- polar liquid High melting/boiling points High melting/boiling points Can conduct electricity when melted Can conduct electricity when melted

Covalent bonds/compounds: Sometimes crystals, sometimes gases, sometimes liquids. Wider range of forms. Sometimes crystals, sometimes gases, sometimes liquids. Wider range of forms. Have lower melting and boiling points than ionic compounds Have lower melting and boiling points than ionic compounds Many don’t dissolve well in water – dissolve well in nonpolar liquids Many don’t dissolve well in water – dissolve well in nonpolar liquids Don’t conduct electricity in water Don’t conduct electricity in water

Polyatomic Ions (partial list from page 195 (193 2 nd edition)) Ammonium……………... Ammonium……………... Nitrate…………………… Nitrate…………………… Permanganate………….. Permanganate………….. Chlorate………………… Chlorate………………… Hydroxide………………. Hydroxide………………. Cyanide…………………. Cyanide…………………. Sulfate…………………... Sulfate…………………... Carbonate………………. Carbonate………………. Chromate……………….. Chromate……………….. Acetate………………….. Acetate………………….. Phosphate………………. Phosphate………………. NH 4 + NH 4 + NO 3 - NO 3 - MnO 4 - MnO 4 - ClO 3 - ClO 3 - OH - OH - CN - CN - SO SO CO 3 2- CO 3 2- CrO 4 2- CrO 4 2- C 2 H 3 O 2 - C 2 H 3 O 2 - PO 4 3- PO 4 3-