1 IB Topic 4: Bonding 4.1: Ionic bonding Essential Idea: Ionic compounds consist of ions held together in lattice structures by ionic bonds. Nature of Science: Use theories to explain natural phenomena – molten ionic compounds conduct electricity but solid ionic compounds do not. The solubility and melting points of ionic compounds can be used to explain observations. (2.2)

2 IB Topic 4: Bonding 4.1: Ionic bonding Understandings: 1.Positive ions (cations) form by metals losing valence electrons 2.Negative ions (anions) form by non-metals gaining electrons. 3.The number of electrons lost or gained is determined by the electron configuration of the atom. 4.The ionic bond is due to electrostatic attraction between oppositely charged ions. 5.Under normal conditions, ionic compounds are usually solids with lattice structures.

3 IB Topic 4: Bonding 4.1: Ionic bonding Applications and Skills: 1.Deduction of the formula and name of an ionic compound from its component ions, including polyatomic ions. 2.Explanation of the physical properties of ionic compounds (volatility, electrical conductivity, and solubility) in terms of their structure.

4 IB Topic 4: Bonding Only one group of elements are stable (nonreactive). Which group? Nobel Gases What is unique about their electron structure? Filled outer s & p orbitals, 8 electrons All other elements react in order to achieve this stable electron configuration.

5 IB Topic 4: Bonding Ionic Bond: Transfer of electrons from metal to non- metal; metal + non-metal Covalent Bond: Sharing of electrons between non- metals; nonmetal + nonmetal

U1. Positive Ions Positive Ions (cations): metals that lose e- Group 1 Lose 1 valence electron Charge of +1: Li +, Na +, K + Group 2 Lose 2 valence electrons Charge of +2: Mg 2+, Ca 2+ Group 13 Lose 3 valence electrons Charge of +3: Al 3+ 6

U2. Negative Ions Negative Ions (anions): non-metals that gain e- Group 15 Gain 3 electrons Charge of -3: N 3-, P 3- Group 16 Gain 2 electrons Charge of -2: O 2-, S 2- Group 17 Gain 1 electron Charge of -1: F -, Cl -, Br -, I - 7

8 U3. Electron Configuration and Ion formation Let’s look at the reaction between sodium and chlorine What is the electron configuration for sodium? What is the electron configuration for chlorine? What do you think they want to do with their electrons?

9 U3. Electron Configuration and Ion formation Sodium configuration: [Ne]3s 1 If Na loses one electron then it would end in [He]2s 2 2p 6 and be stable. Then sodium has 11 protons (11+), but only 10 electrons (10-) so it acquires a charge of 1+ and becomes the sodium ion, Na +. In order for it to lose an electron, something has to gain an electron

10 U3. Electron Configuration and Ion Formation Chlorine configuration: [Ne]3s 2 3p 5 If Cl gains one electron then it would end in [Ne]3s 2 3p 6 and be stable. Then chlorine has 17 protons (17 + ), and 18 electrons (18 - ) so it acquires a charge of 1 - and becomes the chloride ion, Cl -. It will gain the electron from the sodium.

U1 & U2. Ion formation Ions are formed when one or more electrons are transferred from one atom to another. 11

U1 & U2. Ion formation Na transfers 1 e- to Cl Na becomes Na +1, positive ion (cation) Cl becomes Cl -1, negative ion (anion) 12

U4. Ionic bond Ionic bond is formed due to the attraction between oppositely charge ions 13

14 U4. Ionic Bond Reaction between Sodium and Chlorine Since opposite charges attract, the Na + and Cl - ions form an ionic bond. ETD: NaCl LDD: [Na] + [ Cl ] - Formula: NaCl Name: Sodium chloride

15 U3. Electron Configuration and Ion Formation Reaction between Magnesium and Chlorine Magnesium configuration: [Ne]3s 2 If Mg loses two electrons then it would end in [He] 2s 2 2p 6 and be stable. Then magnesium has 12 protons (12+), but only 10 electrons (10-) so it acquires a charge of 2+ and becomes the magnesium ion, Mg 2+. In order for it to lose two electrons, something has to gain two electrons

16 U3. Electron Configuration and Ion Formation Reaction between Magnesium and Chlorine Chlorine configuration: [Ne]3s 2 3p 5 If Cl gains one electron then it would end in [Ne]3s 2 3p 6 and be stable. Then chlorine has 17 protons (17 + ), and 18 electrons (18 - ) so it acquires a charge of 1 - and becomes the chloride ion, Cl -. Since chlorine can only gain one electron and magnesium gives up two electrons, magnesium requires two chlorine atoms.

17 U4. Ionic Bond Reaction between Magnesium and Chlorine Since opposite charges attract, the Mg 2+ and the 2 Cl - ions form an ionic bond. ETD: MgCl Cl LDD: [Mg] 2+ [ Cl ] 2 - Formula: MgCl 2 Name: Magnesium chloride

18 U4. Ionic Bond Reaction between Potassium and Oxygen Potassium configuration: [Ar] 4s 1 Potassium will lose 1 electron and become the potassium ion K +. [Ne] 3s 2 3p 6 Oxygen configuration: [He]2s 2 2p 4 Oxygen will gain 2 electrons and become the oxide ion O 2-. [He]2s 2 2p 6 Two potassium atoms are needed to combine with one oxygen.

19 U4. Ionic Bond Reaction between Potassium and Oxygen ETD: K O K LDD:[K] 2 +1 [ O ] -2 Formula:K 2 O Name:Potassium oxide

20 Reaction between Aluminum and Bromine Diagram the bonding between Al and Br using electron configuration, write the formula, and give the name. U4. Ionic Bond

21 Reaction between Aluminum and Bromine ETD: LDD: Formula: AlBr 3 Name: Aluminum bromide U4. Ionic Bond

22 Transition Metals In most transition elements, inner electrons can become involved in the reaction Iron can lose 2 electrons (Fe 2+ ) or 3 electrons (Fe 3+ ) The name of the Fe 2+ ion is iron (II) or ferrous The name of the Fe 3+ ion is iron (III) or ferric Chromium can lose 2 electrons (Cr 2+ ) or 3 electrons (Cr 3+ ) The name of the Cr 2+ ion is chromium (II) or chromous The name of the Cr 3+ ion is chromium (III) or chromic

23 Summary of Ionic Bonds Formed between a metal ion and a non-metal ion –Metal transfers valence electrons to the non-metal Ions are formed when atoms transfer electrons. –Cations = electron removed, + charge –Anions = electron added, - charge The number of electrons that are transferred is determined by the valence electrons for each atom (dots)

24 Polyatomic ions are ions consisting of two or more atoms bonded together NitrateNO 3 - HydroxideOH - SulfateSO 4 2- CarbonateCO 3 2- PhosphatePO 4 3- AmmoniumNH 4 + Hydrogen carbonate (bicarbonate) HCO 3 - More on chart of ions: nitrite, sulfite, perchlorate, chlorate, chlorite, hypochlorite, silicate A&S 1: Polyatomic Ions

25 MUST KNOW THESE 7 NitrateNO 3 - HydroxideOH - SulfateSO 4 2- CarbonateCO 3 2- PhosphatePO 4 3- AmmoniumNH 4 + Hydrogen carbonate (bicarbonate) HCO 3 - Polyatomic Ion Quiz is April 8! A&S 1: Polyatomic Ions

A & S 1. Naming Ionic Compounds RULE: Cation first, then anion 1. Monatomic cation = name of the element Ca 2+ = calcium ion 2. Monatomic anion = root + -ide Cl  = chloride ion CaCl 2 = calcium chloride

Names of Variable Ions Transition metals and the metals in groups 14 and 15 (except Ag, Zn, Cd, and Al) require a Roman Numeral because they can have more than one charge (form more than one ion). FeCl 3 (Fe 3+ ) iron (III) chloride CuCl (Cu + ) copper (I) chloride SnF 4 (Sn 4+ ) tin (IV) fluoride PbCl 2 (Pb 2+ )lead (II) chloride Fe 2 S 3 (Fe 3+ )iron (III) sulfide

Transition metal ionic compounds indicate charge on metal with Roman numerals FeCl 2 2 Cl - -2 so Fe is +2 iron(II) chloride FeCl 3 3 Cl - -3 so Fe is +3 iron(III) chloride Cr 2 S 3 3 S so Cr is +3 (6/2)chromium(III) sulfide

Naming Ionic Compounds Examples: NaCl ZnI 2 Al 2 O 3 sodium chloride zinc iodide aluminum oxide

Practice 1 Complete the names of the following binary compounds: Na 3 Nsodium ____________ KBrpotassium __________ Al 2 O 3 __________ oxide MgS__________ __________

Practice 1 Complete the names of the following binary compounds: Na 3 Nsodium nitride KBrpotassium bromide Al 2 O 3 aluminum oxide MgSmagnesium sulfide

Practice 2 Complete the names of the following binary compounds with variable metal ions: FeBr 2 iron (_____) bromide CuClcopper (_____) chloride SnO 2 ___(_____ ) ______________ Fe 2 O 3 ________________________ Hg 2 S________________________

Practice 2 Complete the names of the following binary compounds with variable metal ions: FeBr 2 Iron (II) bromide CuClCopper (I) chloride SnO 2 Tin(IV) oxide Fe 2 O 3 Iron (III) oxide Hg 2 SMercury (II) sulfide

NO 3 - nitrate ion NO 2 - nitrite ion Polyatomic Ions

You can make additional polyatomic ions by adding a H + to the ion! CO 3 -2 is carbonate HCO 3 – is hydrogen carbonate H 2 PO 4 – is dihydrogen phosphate HSO 4 – is hydrogen sulfate Polyatomic Ions

Writing Ionic Formulas from Names Write each ion, cation first. Don’t show charges in the final formula. Overall charge must equal zero. –If charges cancel, just write symbols. –If not, use subscripts to balance charges. Use parentheses to show more than one of a particular polyatomic ion. Use Roman numerals indicate the ion’s charge when needed

Writing Ionic Formulas Sodium Sulfate Na + and SO 4 -2 Na 2 SO 4 Iron (III) hydroxide Fe +3 and OH - Fe(OH) 3 Ammonium carbonate NH 4 + and CO 3 –2 (NH 4 ) 2 CO 3

Writing Formula Practice 1 1. aluminum nitrate a) AlNO 3 b) Al(NO) 3 c) Al(NO 3 ) 3 2. copper(II) nitrate a) CuNO 3 b) Cu(NO 3 ) 2 c) Cu 2 (NO 3 ) 3. Iron (III) hydroxide a) FeOHb) Fe 3 OHc) Fe(OH) 3 4. Tin(IV) hydroxide a) Sn(OH) 4 b) Sn(OH) 2 c) Sn 4 (OH)

Writing Formula Practice 1 1. aluminum nitrate a) AlNO 3 b) Al(NO) 3 c) Al(NO 3 ) 3 2. copper(II) nitrate a) CuNO 3 b) Cu(NO 3 ) 2 c) Cu 2 (NO 3 ) 3. Iron (III) hydroxide a) FeOHb) Fe 3 OHc) Fe(OH) 3 4. Tin(IV) hydroxide a) Sn(OH) 4 b) Sn(OH) 2 c) Sn 4 (OH)

Naming Polyatomic Ionic Compounds Contains at least 3 elements There MUST be at least one polyatomic ion (it helps to circle the ions) Examples: NaNO 3 Sodium nitrate K 2 SO 4 Potassium sulfate Al(HCO 3 ) 3 Aluminum bicarbonate or Aluminum hydrogen carbonate

Naming Polyatomic Compounds Practice Match each set with the correct name: 1. Na 2 CO 3 a) magnesium sulfite MgSO 3 b) magnesium sulfate MgSO 4 c) sodium carbonate 2.Ca(HCO 3 ) 2 a) calcium carbonate CaCO 3 b) calcium phosphate Ca 3 (PO 4 ) 2 c) calcium bicarbonate

Naming Polyatomic Compounds Practice Match each set with the correct name: 1. Na 2 CO 3 a) magnesium sulfite MgSO 3 b) magnesium sulfate MgSO 4 c) sodium carbonate 2.Ca(HCO 3 ) 2 a) calcium carbonate CaCO 3 b) calcium phosphate Ca 3 (PO 4 ) 2 c) calcium bicarbonate

43 U5. Lattice Structure Ionic compounds form crystalline solids that have a lattice structure; 3D repeating units of alternating positive and negative ions Sodium Chloride: Each sodium ion is surrounded by up to 6 chloride ions and each chloride ion is surrounded by up to 6 sodium ions.

44 Melting Point: temperature at which change from a solid to a liquid Boiling Point: temperature at which change from a liquid to a gas Volatility - how easily it is converted to gas Important Terms

45 Conductivity- conducts electricity; depends on whether the substance contains electrically charged particles that are free to move through it Solubility - solute’s ability to dissolve in solvent Important Terms

46 A & S 2: Ionic Bond Physical Properties Ionic Compounds: Solid at Room temperature Hard and brittle due to lattice structure Held tighter by strong electrostatic forces in 3D

47 A & S 2: Ionic Bond Physical Properties Ionic Compounds: MP: high BP: high Volitility: low Conductivity: not when solid; must be dissolved or molten to conduct Solubility: dissolve in polar solvents (water), do not dissolve in non-polar solvents (hexane)

48 Electronegativity Difference Ionic bonds: electronegativity differences greater than or equal to 1.7 Compare the electronegativity values between 2 atoms to determine bond type Subtract the smaller value from the larger to determine difference Ex: Na and N: 3.0 – 0.9= 2.1 = IONIC