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BONDING & NOMENCLATURE. Forces that hold groups of atoms together and make them function as a unit. Bonds. Ionic bonds – transfer of electrons Covalent bonds – sharing of electrons. Ionic Bonding. Involves a ________ of electrons ___________ structure.
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BONDING & NOMENCLATURE
Forces that hold groups of atoms together and make them function as a unit. Bonds • Ionic bonds – transfer of electrons • Covalent bonds – sharing of electrons
Involves a ________ of electrons ___________ structure. A regular _________ arrangement of ions in the solid. Ions are _________ bonded. Structure is ________. _______ melting points- because of strong forces between ions. Properties of Ionic Compounds
Sodium Chloride Crystal Lattice Ionic compounds form solid crystalsat ordinary temperatures. Ionic compounds organize in a characteristic crystal lattice of alternating positive and negative ions. All saltsare ionic compoundsand formcrystals.
Involves a ______________ of electrons ___________ shapes vary __________ bond than Ionic compounds __________ melting points due to the weaker bond. Called _____________ not compounds. Properties of Covalent Molecules
Metallic Bonding Strong forces of attraction are responsible for the high melting point of most metals.
Metallic Bonding • The chemical bonding that results from the attraction between metal cationsand the surrounding sea of electrons • Vacant p and dorbitals in metal's outer energy levels overlap, and allow outer electrons to move freely throughout the metal • Valence electrons do not belong to any one atom
+ + + + + + + + + + + + Malleable
Electrons allow atoms to slide by. + + + + + + + + + + + + Malleable
+ - + - - + - + + - + - - + - + Ionic solids are brittle
Strong Repulsion breaks crystal apart. - + - + - + - + + - + - - + - + Ionic solids are brittle
The Octet Rule – Ionic Compounds Ionic compounds form so that each atom, by gaining or losing electrons, has an octet of electrons in its highest occupied energy level. Metals lose electrons to form cations Nonmetals gains electrons to form anions
Ionic Bonding:The Formation of Sodium Chloride • Sodium has 1 valence electron • Chlorine has 7 valence electrons • An electron transferred gives each an octet Na:1s22s22p63s1 Cl:1s22s22p63s23p5
Ionic Bonding:The Formation of Sodium Chloride This transfer forms ions, each with an octet: Na+1s22s22p6 Cl-1s22s22p63s23p6
Ionic Bonding:The Formation of Sodium Chloride The resulting ions come together due to electrostatic attraction (opposites attract): Na+ Cl- The net charge on the compound must equal zero
Ionic Bonding Na Cl
Ionic Bonding Na+ Cl-
All the electrons must be accounted for! Ionic Bonding Ca P
Ionic Bonding Ca P
Ionic Bonding Ca+2 P
Ionic Bonding Ca+2 P Ca
Ionic Bonding Ca+2 P-3 Ca
Ionic Bonding Ca+2 P-3 Ca+2 P
Ionic Bonding Ca Ca+2 P-3 Ca+2 P
Ionic Bonding Ca Ca+2 P-3 Ca+2 P
Ionic Bonding Ca+2 Ca+2 P-3 Ca+2 P-3
Ionic Bonding Ca3P2 Formula Unit
Examples of Ionic compounds MgCl2 Magnesium chloride: Magnesium loses two electrons and each chlorine gains one electron Na2O Sodium oxide: Each sodium loses one electron and the oxygen gains two electrons Aluminum sulfide: Each aluminum loses two electrons (six total) and each sulfur gains two electrons (six total) Al2S3
Ionic Compound Formulas www.lab-initio.com
Cation: A positive ion Mg2+, NH4+ Anion: A negative ion Cl-, SO42- Ions
Predicting Ionic Charges Group 1: Lose 1 electron to form 1+ ions H+ Li+ Na+ K+
Predicting Ionic Charges Group 2: Loses 2 electrons to form 2+ ions Be2+ Mg2+ Ca2+ Ba2+ Sr2+
Predicting Ionic Charges Loses 3 electrons to form 3+ ions Group 13: B3+ Al3+ Ga3+
Predicting Ionic Charges Lose 4 electrons or gain 4 electrons? Group 14: Neither!Group 13 elements rarely form ions.
Predicting Ionic Charges Nitride N3- Gains 3 electrons to form 3- ions Group 15: Phosphide P3- As3- Arsenide
Predicting Ionic Charges Oxide O2- Group 16: Gains 2 electrons to form 2- ions S2- Sulfide Se2- Selenide
Predicting Ionic Charges Group 17: Gains 1 electron to form 1- ions F1- Fluoride Cl1- Chloride Br1- Bromide I1- Iodide
Predicting Ionic Charges Group 18: Stable Noble gases do not form ions!
Predicting Ionic Charges Many transition elements have more than one possible oxidation state. Groups 3 - 12: Iron(II) = Fe2+ Iron(III) = Fe3+
Predicting Ionic Charges Some transition elements have only one possible oxidation state. Groups 3 - 12: Zinc =Zn2+ Silver = Ag+
Writing Ionic Compound Formulas Example: Barium nitrate 1. Write the formulas for the cation and anion, including CHARGES! 2. Check to see if charges are balanced. 3. Balance charges , if necessary, using subscripts.Use parentheses if you need more than one of apolyatomic ion. Ba2+ ( ) NO3- 2 Not balanced! • Ba(NO3)2
Writing Ionic Compound Formulas Example:Ammonium sulfate 1. Write the formulas for the cation and anion, including CHARGES! 2. Check to see if charges are balanced. 3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. ( ) NH4+ SO42- 2 (NH4)2SO4 Not balanced!
Writing Ionic Compound Formulas Example: Iron(III) chloride 1. Write the formulas for the cation and anion, including CHARGES! 2. Check to see if charges are balanced. 3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Fe3+ Cl- 3 FeCl3 Not balanced!
Writing Ionic Compound Formulas Example: Aluminum sulfide 1. Write the formulas for the cation and anion, including CHARGES! 2. Check to see if charges are balanced. 3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Al3+ S2- 2 3 Al2S3 Not balanced!
Writing Ionic Compound Formulas Example: Magnesium carbonate 1. Write the formulas for the cation and anion, including CHARGES! 2. Check to see if charges are balanced. Mg2+ CO32- MgCO3 They are balanced!
Writing Ionic Compound Formulas Example: Zinc hydroxide 1. Write the formulas for the cation and anion, including CHARGES! 2. Check to see if charges are balanced. 3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. ( ) Zn2+ OH- 2 Zn(OH)2 Not balanced!
Cationfirst, then anion Monatomic cation = name of the element Ca2+ = calcium ion Monatomic anion= root + -ide Cl-=chloride CaCl2 = calcium chloride Naming Ionic Compounds
some metal forms more than one cation use Roman numeral in name PbCl2 Pb2+ is cation PbCl2 = lead(II) chloride Naming Ionic Compounds(continued) Metals with multiple oxidation states