+  2 Na (s) Cl2 2 NaCl Ionic compound

The Periodic Law In the modern periodic table, elements are arranged in order of increasing atomic number. In the modern periodic table, the elements are arranged in order of increasing atomic number. Interpreting Diagrams How many elements are there in the second period?

Electronegativity vs. atomic number 04/10/99

Ionization energy vs. atomic number 04/10/99

Valence Electrons When atoms combine, only the valence electrons are involved. Valence electrons are the electrons in the atom’s highest occupied energy level. The number of valence electrons largely determines the chemical properties of an element.

Valence Electrons Group 1A Group 6A Group 7A Group 8A Lithium Oxygen Fluorine Neon On your handout, draw the Lewis dot structures for the representative elements in periods 1 through 4. Sodium

Valence Electrons Electron dot structures are diagrams that show valence electrons as dots.

The Octet Rule The Octet Rule When forming compounds, atoms tend to achieve the electron configuration of a noble gas. Atoms of metals tend to lose their valence electrons. Atoms of some non-metals tend to gain electrons or to share electrons with another nonmetal. When an atom forms an ion, it is no longer neutral, it has a charge, called its oxidation number.

Ion Notation HOW TO WRITE AN ION: [ELEMENT SYMBOL]Charge Examples: Na+ oxidation number = +1 Cl- oxidation number = -1 Al3+ oxidation number = +3 ** Charge/Oxidation number is a SUPERSCRIPT

Formation of Cations Metals have LOW electronegativity and LOW ionization energy so they will LOSE electrons to form cations, positive ions. The electron configuration of the sodium ion is the same as that of a neon atom.

Formation of Cations Using electron dot structures, you can show the ionization more simply.

Formation of Cations A magnesium atom attains the electron configuration of neon by losing both valence electrons. The loss of valence electrons produces a magnesium cation with a charge of 2+.

Formation of Anions Non-metals have HIGH electronegativity and HIGH ionization energy so they will GAIN electrons to form anions, negative ions. Both a chloride ion and the argon atom have an octet of electrons in their highest occupied energy levels.

Formation of Anions A chlorine atom attains the electron configuration of argon by gaining an electron. The gaining of a valence electron produces a chlorine anion with a charge of 1-.

Formation of Anions Oxygen is in Group 6A. How many valence electrons? What noble gas configuration will it have when it forms an ion?

Charges of Ions Chlorine ion: Chlorine atom: 18 electrons 18- 17 protons 17 + Neutral 0 Chlorine ion: 18 electrons 18- 17 protons 17 + Net charge 1- Magnesium atom: 12 electrons 12- 12 protons 12 + Neutral 0 Magnesium ion: 10 electrons 10- 12 protons 12 + Net charge 2+

Predicting Ionic Charges Group 1A: Lose 1 electron to form 1+ ions H1+ Li1+ Na1+ K1+ Rb1+

Predicting Ionic Charges Group 2A: Loses 2 electrons to form 2+ ions Be2+ Mg2+ Ca2+ Sr2+ Ba2+

Predicting Ionic Charges Loses 3 electrons to form 3+ ions Group 3A: B3+ Al3+ Ga3+

Predicting Ionic Charges Neither! Group 4A elements rarely form ions EXCEPTION: Sn and Pb!! Treat like transition metals Do they lose 4 electrons or gain 4 electrons? Group 4A:

Predicting Ionic Charges Nitride Gains 3 electrons to form 3- ions Group 5A: P3- Phosphide As3- Arsenide

Predicting Ionic Charges Oxide Gains 2 electrons to form 2- ions Group 6A: S2- Sulfide Se2- Selenide

Predicting Ionic Charges Gains 1 electron to form 1- ions Group 7A: F1- Fluoride Br1- Bromide Cl1- Chloride I1- Iodide

Predicting Ionic Charges Stable noble gases do not form ions! Group 8A:

Ions and the octet rule 04/10/99 Which ions have fewer than 8 valence electrons? H+ has 0 valence electrons Li+ has 2 valence electrons (similar to He) Be2+ has 2 valence electrons B3+ has 2 valence electrons

Br P Ne Al Ca Ion Ions and the octet rule Kr Ar (3) Ne (0) Ne (3) 04/10/99 Complete the chart in your handout. Br P Ne Al Ca Nearest Noble Gas (spaces removed) Kr Ar (3) Ne (0) Ne (3) Ar (2) (1) Ion Br- P 3– none Al 3+ Ca 2+

Predicting Ionic Charges Many transition elements have more than one possible charge. Also Pb and Sn (Group 4A) Iron (II) = Fe2+ Note the use of Roman numerals to show charges Iron (III) = Fe3+

Predicting Ionic Charges Roman numerals: V 5 VI 6 I 1 VII 7 II 2 VIII 8 III 3 IX 9 IV 4 X 10

Predicting Ionic Charges Group B elements: Some transition elements have only one possible oxidation state, such as these three: Silver = Ag1+ Zinc = Zn2+ Cadmium = Cd2+

Write symbols for these cations: Potassium ion Magnesium ion Copper (II) ion Oxygen ion (Oxide) Arsenic ion (Arsenide) Bromine ion (Bromide) K+ Mg2+ Cu2+ O2- As3- Br-

HOMEWORK #1: Write the ion symbols Chromium (VI) ion Barium ion Mercury (II) ion Phosphide Fluoride Oxide Cr6+ Ba2+ Hg2+ P3- F- O2-

HOMEWORK #2: 1. Write ion notation: Nitrogen Sulfur Barium Lithium Beryllium Iodine N3- S2- Ba2+ Li+ Be2+ I-

HOMEWORK #2: High EN – form anions High IE – form anions Noble gases have full valence shell

HOMEWORK #2: 5. How many valence electrons? Cs Rb Ga S Sr 1 3 6 2

HOMEWORK #2: 5. Metals or non-metals? Mg C H Zn Se metal non-metal

HOMEWORK#3: Naming Na+ Ca2+ Al3+ Fe3+ Fe2+ Mn2+ Li+ Sodium ion Calcium ion Aluminum ion Iron (III) ion Iron (II) ion Manganese (II) ion Lithium ion

Cl- N3- Br- O2- S2- Chloride Nitride Bromide Oxide Sulfide HOMEWORK #3: Naming Cl- N3- Br- O2- S2- Chloride Nitride Bromide Oxide Sulfide

Naming Ions NAMING CATIONS (positive metal ions): 04/10/99 NAMING CATIONS (positive metal ions): Representative Elements: Just write the name of the metal. Ca2+ = calcium ion Transition metals (and Pb & Sn) can have more than one possible charge. Use a roman numeral to indicate the charge Iron (II) = Fe2+ Iron (III) = Fe3+

Exceptions: Some of the transition metals have only one ionic charge: Do not use roman numerals for these: Silver is always 1+ (Ag+) Cadmium and Zinc are always 2+ (Cd2+ and Zn2+)

Naming Ions NAMING ANIONS (non-metal, negative ions): 04/10/99 NAMING ANIONS (non-metal, negative ions): Anions are always the same charge (Cl always -1) Change the monatomic element ending to – ide F1- a Fluorine atom will become a Fluoride ion. N3- a Nitrogen atom will become a Nitride ion.

Practice: Name these ions K+ Mg2+ Cu2+ I- As3- S2- Potassium ion Magnesium ion Copper (II) ion Iodide Arsenide Sulfide

Overview: Types of Bonds 04/10/99 3 bond types : ionic, covalent and metallic. Ionic bonding occurs between: a metal and a non-metal. Electrons are transferred. Covalent bonding occurs between two non-metals. Electrons are shared. Metallic bonding occurs between: two metals.

Overview: Types of Bonds 04/10/99 Identify each compound as ionic or covalent MgO (ionic), CaCl2 (ionic), PbCl2 (ionic), CCl4 (covalent), CH4 (covalent) SO2 (covalent),

Ionic bonding e– 1) 2) Na Cl 3) Cl– Na+ Cl– Na+ 04/10/99 Ionic bonding involves 3 steps: loss of electron(s) by a metal, gain of electron(s) by a non-metal, ** number of electrons lost by metal = number gained by non-metal 3) attraction between positive and negative ions e– 1) 2) Na Cl 3) Cl– Na+ Cl– Na+

Properties of Ionic Compounds Properties of Ionic Compounds (formed between a metal and a non-metal) What are three properties of ionic compounds? crystalline solids at room temperature called a CRYSTAL LATTICE high melting points. conduct an electric current when melted or dissolved in water. Crystalline solids are very stabel so they are hard to change ----high melting point.

Properties of Ionic Compounds Ionic compounds can conduct an electric current when melted or dissolved in water. When sodium chloride melts, the sodium and chloride ions are free to move throughout the molten salt. If a voltage is applied, positive sodium ions move to the negative electrode (the cathode), and negative chloride ions move to the positive electrode (the anode). Predicting What would happen if the voltage was applied across a solution of NaCl dissolved in water?

Formation of Ionic Compounds NaCl (table salt) is arranged in a 3-D pattern = CRYSTAL LATTICE Sodium cations and chloride anions form a repeating three-dimensional array in sodium chloride (NaCl). Inferring How does the arrangement of ions in a sodium chloride crystal help explain why the compound is so stable?

Formation of Ionic Compounds Ionic Bonds The electrostatic forces that hold ions together in ionic compounds are called ionic bonds. Sodium loses 1 electron; chlorine gains 1 electron

Ionic bonding (Li + Cl) 04/10/99 Write out the dot structures for lithium chloride. Start by writing the dot structures for each atom. Li Cl [ Cl ]– [Li]+ Lithium loses 1 electron; chlorine gains 1 electron

Ionic bonding: Mg + O Mg + O  [Mg]2+[O]2– O Mg [ O ]2– [Mg]2+ 04/10/99 Mg + O  [Mg]2+[O]2– O Mg [ O ]2– [Mg]2+ Magnesium loses 2 electrons; oxygen gains 2 electrons

Formation of Ionic Compounds TRANSFER OF ELECTRONS Each calcium loses 2 electrons; TWO chlorine atoms gain 1 electron each

Naming Ionic Compounds 1. Name the cation first, then anion 2. Monatomic cation = name of the element Ca2+ = calcium ion 3. Monatomic anion = root + -ide Cl- = chloride CaCl2 = calcium chloride

Naming Ionic Compounds (Metals with multiple oxidation states) For transition metals use a Roman numeral in the name: PbCl2 Pb2+ is the lead (II) cation PbCl2 = lead (II) chloride

Polyatomic ions are… Groups of atoms that stay together, have an overall charge, and one name. Usually end in –ate or -ite Acetate: C2H3O2- Carbonate: CO32- Sulfate: SO42- Sulfite: SO32- Nitrate: NO3- Nitrite: NO2- Phosphate: PO43- Phosphite: PO33-

More Common Polyatomic Ions The two polyatomic ions ending in –ide: Hydroxide: OH- Cyanide: CN- Ammonium: NH4+ (One of the few positive polyatomic ions)

Naming Ionic Compounds with polyatomic ions 1. Name the cation first, then the anion 2. Polyatomic cation = name of the ion NH4+ = ammonium 3. Polyatomic anion = name of the ion SO42- = sulfate (NH4)2SO4 = ammonium sulfate

Practice by writing the name for polyatomic ions Circle the anion and cation in each compound MgSO4 NH4Cl AlPO4 Magnesium sulfate Ammonium chloride Aluminum phosphate

Writing Ionic Compound Formulas 1.Write the symbols for the cation and anion, including CHARGES! 2. Check to see if charges are balanced. 3. Balance charges , if necessary, using subscripts. Use the criss-cross method to balance subscripts.

Hints: If you need more than one polyatomic ion to balance the charges put ( ) around the ion. If anions end in -ide they are monoatomic [Except OH-, hydroxide & CN-, cyanide] If anion ends in -ate or –ite, then it is polyatomic

Writing Ionic Compound Formulas Example: Iron (III) chloride (note the 2 word name) 1. Write the symbols for the cation and anion, including CHARGES! Fe3+ Cl- 1 3 Now balanced. 2. Check to see if charges are balanced. Not balanced! = FeCl3 3. Balance charges , if necessary, using subscripts. Use the criss-cross method to balance subscripts. 4. Fe3+ + Cl-  FeCl3

Writing Ionic Compound Formulas Example: Aluminum sulfide (note the 2 word name) 1. Write the symbols for the cation and anion, including CHARGES! Al3+ S2- 2 3 2. Check to see if charges are balanced. Now balanced. Not balanced! = Al2S3 3. Balance charges , if necessary, using subscripts. Use the criss-cross method to balance subscripts.

Writing Ionic Compound Formulas Example: Magnesium carbonate (note the 2 word name) 1. Write the symbols for the cation and anion, including CHARGES! Mg2+ CO32- 2. Check to see if charges are balanced. They are balanced! = MgCO3

Writing Ionic Compound Formulas Example: Barium nitrate (note the 2 word name) 1. Write the symbols for the cation and anion, including CHARGES! ( ) Ba2+ NO3- 2 1 2. Check to see if charges are balanced. Now balanced. Not balanced! 3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Use the criss-cross method to balance subscripts. = Ba(NO3)2

Writing Ionic Compound Formulas Example: Ammonium sulfate (note the 2 word name) ( ) 1. Write the symbols for the cation and anion, including CHARGES! NH4+ SO42- 2 1 Now balanced. 2. Check to see if charges are balanced. Not balanced! = (NH4)2SO4 3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Use the criss-cross method to balance subscripts.

Writing Ionic Compound Formulas Example: Zinc hydroxide (note the 2 word name) 1. Write the symbols for the cation and anion, including CHARGES! ( ) Zn2+ OH- 1 2 Now balanced. 2. Check to see if charges are balanced. Not balanced! = Zn(OH)2 3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Use the criss-cross method to balance subscripts.

Writing Ionic Compound Formulas Example: Aluminum phosphate (note the 2 word name) 1. Write the symbols for the cation and anion, including CHARGES! Al3+ PO43- 2. Check to see if charges are balanced. They ARE balanced! = AlPO4

HOMEWORK #4: Form an ionic bond? Mg & O As & Br Ca & K F & Li Ar & H Metal & nonmetal - YES 2 non-metals - NO 2 metals - NO Noble gas - NO

HOMEWORK#5: Naming KI Potassium Iodide SnBr4 Tin (IV) Bromide Mg3P2 NaF Al2Se3 MgBr2 KCl Potassium Iodide Tin (IV) Bromide Magnesium Phosphide Sodium Fluoride Aluminum Selenide Magneium Bromide Potassium Chloride

HOMEWORK#5: Naming FeCl2 Iron (II) Chloride FeCl3 Iron (III) Chloride Al2S3 Iron (II) Chloride Iron (III) Chloride Aluminum Sulfide

HOMEWORK#5: Naming PbO Lead (II) Oxide TiI4 Titanium (IV) Iodide Co3N2 Mg3P2 TiSe Cu2O V3P5 Zn3N2 Lead (II) Oxide Titanium (IV) Iodide Cobalt (II) Nitride Magnesium Phosphide Titanium (II) Selenide Copper (I) Oxide Vanadium (V) Phosphide Zinc Nitride

HOMEWORK#5: Naming Li2O Lithium Oxide CuO Copper (II) Oxide PbS Lead (II) Sulfide