U NIT 5 C HEMICAL B ONDING Chapter 6.1 Lewis Dot Diagrams & Ions

S TABLE E LECTRON C ONFIGURATIONS When is an atom unlikely to react? When the outer shell (highest occupied energy level) is ________ with electrons ____ e - for Octet Rule Noble gases are the most ______ elements. The highest occupied energy level is completely filled. Elements tend to _______ to achieve electron configurations similar to those of noble gases.

S TABLE E LECTRON C ONFIGURATIONS ___________ properties of an element depend on the number of valence electrons. Electron dot diagram - [ ___________ _________ ] is alternative to standard electron shell diagram Dot diagram emphasizes valence electrons (inner shells hidden)

E LECTRON C ONFIGURATION AND L EWIS D OT D IAGRAMS Lewis Dot Diagram Both of these mean the same thing

L EWIS D OT D IAGRAM Element symbol represents: ____________ AND All ________ core electrons Dots represent: ___________ electrons (outer shell – Highest occupied energy level) F

S TABLE E LECTRON C ONFIGURATIONS – L EWIS D OT D IAGRAMS

F ORMATION OF I ONS When an atom _______ or ________ an electron(s)  atom is no longer neutral. # of Protons NO LONGER EQUAL # of electrons Definition: ION = _______ (or group of atoms) with positive ( +) or negative ( -) net ________ charge.

F ORMATION OF I ONS ANION = Ion with a ______________ (-) charge [Memory aid: anion = A N egative ION ] Example: Chlorine atomic # 17 Halogen Family/Group 7A 7 Valence Electrons Neutral (but not stable) - 17 protons and 17 electrons To become stable – ______ 1 electron in outer e - shell Now have 1 more e - than proton = -1 net charge Symbol is written ______ or _______

F ORMATION OF I ONS Naming Anions : Part of element name + suffix “______” Example: Chlorine ion becomes “ chlor” + “ide” Cl - is called a chloride ion F - is the ___________ ion Br - is the ___________ ion I - is the ______________ ion

F ORMATION OF I ONS CATION = Ion with a _____________ charge Example: Sodium atomic # 11 Alkali Metal Family/Group 1A 1 Valence Electron Neutral (but not stable) -11 protons and 11 electrons To become stable – _______ the 1 electron in outer e - shell Now has 1 more proton than electron = 1 + net charge Symbol is written ______ or ______

F ORMATION OF I ONS Naming ___________: Use the normal element name Na + is called a sodium ion Li + is the __________ ion Cs + is the __________ ion Fr + is the __________ ion

B ONDING Elements achieve stable electron configurations by _____________ or ___________ electrons between atoms Transferring Electrons - Those with ___ valence electrons “_____” them These elements “lose” valence electrons OR Those with ____ valence electrons “_________” them These elements “gain” electrons

F ORMATION OF I ONS & B ONDING Sodium reacts with chlorine  electron transferred from sodium to chlorine Each atom ends up more stable

I ONIC B ONDING Chemical bond = ________ that holds atoms or ions together as a unit. Opposites ________ Particle(s) with negative charge attracts particle(s) with positive charge. Ionic bond Force that holds cations and anions together and which involves the _____________ of electrons. Bond occurs between a ________ and a nonmetal

I ONIC B ONDING Ionic Compounds What is the chemical formula for magnesium chloride? Mg and Cl First determine the Lewis Dot Diagram and Ions for each element : IonsLewis Dot

I ONIC B ONDING Mg atom cannot reach a ________ electron configuration by giving up just 1 valence electron or __________ with just 1 chlorine atom.

I ONIC B ONDING Mg transfers ___ electrons, one to each of the ____ Cl atoms. After transfer  Charge on the magnesium ion is 2 + Charge on the 2 chloride ions is 1 -

I ONIC B ONDING Formula for magnesium chloride is MgCl 2

P ROPERTIES OF I ONIC C OMPOUNDS The properties of sodium chloride are typical of ________ compounds. ________ melting point sodium chloride melts ~800°C When solid - ______ conductor of electric current When liquid (melted) - _______ conductor of electric current. Brittle - crystals shatter when struck with a mallet