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IONIC BONDING

IONIC BONDING. Ms. Timmerman Belton High School. Chemical Bond. Definition – a mutual electrical attraction between the nuclei and valence electrons of different atoms Valence electrons are electrons available to form a chemical bond. These electrons are in the outermost s and p orbital

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IONIC BONDING

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  1. IONIC BONDING Ms. Timmerman Belton High School

  2. Chemical Bond • Definition – a mutual electrical attraction between the nuclei and valence electrons of different atoms • Valence electrons are electrons available to form a chemical bond. These electrons are in the outermost s and p orbital • Bonding occurs to increase the stability of an atom

  3. There are two types of Chemical Bonds • COVALENT • Occurs when electrons are shared between two non-metals • We will study these after break • IONIC • Occurs between METALS and NON – METALS

  4. Ionic Bonding • Ionic bonding occurs when oppositely charged ions are attracted to one another. • The positive and negative charges must balance one another. • The total overall charge must always equal zero(0) 1+ 1- 0overall charge …two happy ice cream cone !s

  5. Formation of Positive Ions • Metals LOSE electrons and form POSITIVE (+) ions. • Positively charged ions are called cations • Metals (main group elements, s & p blocks) • Number electrons lost = valence electrons • Ion charge = number of electrons lost • Transition metals (d-block) are multivalent • Use the chart to determine the charge

  6. Formation of Negative Ions • Nonmetals GAIN electrons and form NEGATIVE(-)ions. • Negatively charged ions are called anions • Number of electrons gained = 8 – valence electrons • Ion charge = number of electrons gained

  7. Calculating the number of Valence Electrons • Simple, look at periodic table! • On your periodic table, write the # of valence electrons for each main group

  8. Practice Problems • How many valence electrons are in the following elements? • Mg • 2 val. electrons • F • 7 val. electrons • Na • 1 val. electron • Al • 3 val. electrons

  9. To keep track of valence electrons, we use an electron – dot structures • Electron dot diagrams represent VALENCE electrons. 1) Write the symbol of the element. 2) Draw dots to represent valence electrons

  10. Practice Problems • Draw the electron dot structures for the following atoms: • Carbon • Neon • Barium • Silicon

  11. Noble Gases • Noble gas are extremely stable due to a completely filled s and p orbital • Noble gases have 8 val. Electrons (except He) • All the other elements want to be like a Noble Gas • Octet Rule: Atoms lose, gain, or share to reach an octet (8)of valence electrons.

  12. Determining the Charge of Ions • Remember – Ions are positively or negatively charged atoms • Ions have either gained or lost electrons • Start with drawing electron dot structure, then determine how many electrons need to be gained or lost to achieve an octet • Example) Fluorine

  13. Determining the Charge of Ions • Refer to Periodic Table!!

  14. Practice Problems • Determine the Charge of the following Ions • Nitrogen • -3 • Lithium • +1 • Radium • +2 • Chlorine • -1

  15. Making Ionic Compounds • Remember an Ionic compound is between a cation and an anion. • The positive and negative charges must balance each other out • The net charge must always equal zero!! • Why do atoms bond? • Independent atoms are at a relatively high potential energy. • Bonding allows atoms to become more stable

  16. 1). Ionic bond – electron from Na is transferred to Cl, this causes a charge imbalance in each atom. The Na becomes (Na+) and the Cl becomes (Cl-), charged particles or ions.

  17. Electron Dot Structure of Electron Pushing Model

  18. Electron Dot Structure for Ionic Compounds • We will use arrows to show the movement of electrons for ionic compounds. • The electrons always go from Cations (metal) to Anions (non-metal) • Therefore, your arrow always points to the nonmetal • Example) Na and Cl

  19. Writing Formulas for Ionic Compounds • Step One – Write the ions for each atom involved in the bond. • Step Two – Balance the charges to make the sum equal zero • Example) Potassium and Oxygen • 1) K+1 and O-2 • 2) K2O K+ O2- K+ No subscript is an understood ONE Subscript tells you the number of atoms

  20. Writing Formulas Hydrogen and Fluorine Lithium and Oxygen HF Li+ O2- H+ F- Li+ Al3+ O2- Li2O Non Metal/Anion Metal/Cation O2- Al3+ Aluminum and Oxygen O2- Al2O3

  21. Putting Ions Together – Criss Cross Method Na+ + Cl- = NaCl Ca+2 + Cl- = CaCl2 Ca+2 + O-2= CaO Na+ + O-2 = Na2O Al+3 + S-2 = Al2S3 Ca+2 + N-3 = Ca3N2 You try these! Li+ + Br- = LiBr Mg+2 + F- = MgF2 Al+3 + I- = AlI3 Sr3P2 KCl Sr+2 + P-3 = K+ + Cl- =

  22. Naming Ionic Compounds • There are three types of ionic compounds and each one has a different naming system • Binary Compounds – 2 ions bonded together • Multivalent Compounds – transition metal bonded to a non-metal • Polyatomic Compounds – more than 2 ions bonded together • Refer to your table of common polyatomic Ions for naming

  23. Binary Ionic Compounds • Remember in writing the formula, put cation first and anion second • Rules for naming: • 1) Name the first element • 2) Change the ending of the second element to –ide • For example) • CaCl2 = calcium chloride • MgS = magnesium sulfide

  24. Practice Problems • Name the following compounds • 1) LiI • Lithium Iodide • 2) BaF2 • Barium Fluoride • 3) KCl • Potassium Chloride • 4) CaBr2 • Calcium Bromide

  25. Practice Problems • Give the following formulas for the binary compounds • 1) aluminum sulfide • Al2S3 • 2) potassium oxide • K2O • 3) boron fluoride • BF3 • 4) barium oxide • BaO

  26. Naming Multivalent Compounds • Transition Metals (d-block) can have multiple valence electron numbers • Therefore you must specify the charge when writing the name. • Rules to naming: • 1) Name the first element • 2) Show the charge of the ion with Roman numerals • 3) Change the ending of the second element to –ide • Example) Cu2S = copper (II) sulfide

  27. Practice Problems • Write the name of the following multivalent compounds • 1) PbBr2 • Lead (II) bromide • 2) MnO • Manganese (II) oxide • 3)Fe2S3 • Iron (III) sulfide

  28. Practice Problems • Write the formula for the following compounds • 1) iron (II) sulfide • FeS • 2) cobalt (III) sulfide • Co2S3 • 3) manganese (II) phosphide • Mn3P2 • 4) chromium (III) flouride • CrF3

  29. Naming Ionic Compounds with Polyatomic Ions • Polyatomic Ions contain more than one element • There is a list of common polyatomic ions with their names and formulas • *** Always treat polyatomic ions as if they are one element. They act as a group. • Naming Rules: • Name the first element • Name the polyatomic ion (DON’T change ending to –ide)

  30. Practice Problems • Name the following compounds • 1) LiNO3 • Lithium nitrate • 2) Ba(OH)2 • Barium hydroxide • 3) AlPO4 • Aluminum phosphate • 4) BeClO2 • Beryllium chlorite

  31. Practice Problems • Give the following formulas for the compound • 1) sodium phosphate • Na3PO4 • 2) calcium hydroxide • Ca(OH)2 • 3) aluminum nitrate • Al(NO3)3 • 4) lead (II) carbonate • PbCO3

  32. Oxidation Numbers • Definition – A number that indicates the general distribution of electrons among the bonded atoms • Oxidation number of a neutral element is ZERO • In a compound, the sum of all atoms oxidation numbers equals ZERO • For Ionic compounds, the oxidation number equals the ion charge

  33. Oxidation Number Practice • Determine the oxidation number for…. • 1) Mg = ______ • 2) In MgO, the oxidation number of the Mg ion is _____ and Oxygen ion is _______. • 3) In Ni (III) N, the oxidation number of the Ni ion is _______ and the nitrogen ion is ______. • *** Notice the sum of atoms is always ZERO for neutral compounds. ZERO +2 -2 +3 -3

  34. Flow Chart for Naming Does the compound have more than 2 elements? YES NO You have a binary compound. Is your metal multivalent? You have a polyatomic Compound. Is your metal multivalent? NO YES NO YES • Naming: • Name cation • In roman numerals put charge of metal • Name anion changing ending to -ide • Naming: • Name metal • In roman numerials put charge of metal • Name polyatomic ion • Naming: • Name cation • Name anion changing ending to -ide • Naming: • Name metal • Name polyatomic ion • Or • Name polyatomic • Name anion changing ending to -ide

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