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U NIT 5 I ONIC B ONDING & N AMING Chapter 6.1 Lewis Dot Diagrams & Ions.

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Presentation on theme: "U NIT 5 I ONIC B ONDING & N AMING Chapter 6.1 Lewis Dot Diagrams & Ions."— Presentation transcript:

1 U NIT 5 I ONIC B ONDING & N AMING Chapter 6.1 Lewis Dot Diagrams & Ions

2 S TABLE E LECTRON C ONFIGURATIONS When is an atom unlikely to react? When the outer shell (highest occupied energy level) is filled with electrons 8 e - for Octet Rule Noble gases are the most stable elements. The highest occupied energy level is completely filled. Elements tend to react to achieve electron configurations similar to those of noble gases.

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

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

5 L EWIS D OT D IAGRAM Element symbol represents: Nucleus AND All inner core electrons Dots represent: Valence electrons (outer shell – Highest occupied energy level) F

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

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

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

17 F ORMATION OF I ONS Naming Anions : Part of element name + suffix “ide” Example: Chlorine ion becomes “ chlor” + “ide” Cl - is called a chloride ion F - is the fluoride ion (“fluor” + “ide”) Br - is the bromide ion (“brom” + “ide”) I - is the iodide ion (“iod” + “”ide”)

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

19 F ORMATION OF I ONS Naming Cations: Use the normal element name + ion Na + is called a sodium ion Li + is the lithium ion Cs + is the cesium ion Fr + is the francium ion

20 B ONDING Elements achieve stable electron configurations by transferring or sharing electrons between atoms Transferring Electrons - Those with <4 valence electrons “LEND” them These elements “lose” valence electrons OR Those with >4 valence electrons “BORROW” them These elements “gain” electrons

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

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

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

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

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

26 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: Mg 2+, Cl - IonsLewis Dot

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

28 I ONIC B ONDING Mg atom cannot reach a stable electron configuration by giving up just 1 valence electron or reacting with just 1 chlorine atom. Mg + 2Cl OR

29 I ONIC B ONDING Formula for magnesium chloride is MgCl

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

31 E XIT S LIP Draw the Lewis Dot Diagrams for the Nitrogen Family. Provide and name the ions for Oxygen, Calcium, and Sulfur. What is the chemical formula for Aluminum Fluoride? Show the steps you used to determine the formula.


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