Ions and Ion formation Ions are atoms with a charge due to more or fewer electrons then protons

Ions and the octet rule BrPNeAlCa Noble gas (spaces) Kr (1) Ion Br – Ar (3) P 3– Ne (0) none Ne (3) Al 3+ Ar (2) Ca 2+ Ions of s and p block elements form in order to have a lower energy state by being isoelectronic to a noble gas.

Cl – Na + Cl – Ionic bonding Ionic bonding involves 3 steps (3 energies) 1) loss of an electron(s) by one element(ionization energy), 2) gain of electron(s) by a second element (electron affinity), 3) attraction between positive and negative ions. Na Cl e–e– 1) 2) 3) Na + Cation = positive ionAnion = negative ion

Ionic bonding (Li + Cl) Ionic bonding (stealing/transfer of electrons) can be represented in three different ways Li + Cl  [Li] + [Cl] – 3p + 4n 0 2e - 1e - 17p + 18n 0 7e - 8e - 2e - 1e - 3p + 4n 0 2e - 17p + 18n 0 8e - 8e - 2e Li Cl [ Cl ] – [Li] +

Ionic bonding: Mg + O Mg + O  [Mg] 2+ [O] 2– 12p + 12n 0 2e - 8e - 2e - 1e - [ O ] 2– [Mg] 2+ 6e - 2e - 8n 0 8p + 1e - 8e - 2e - 8n 0 8p + 12p + 12n 0 2e - 8e - O Mg For more lessons, visit

Structure of Ionic Compounds They form network solids, also known as crystals. Positive and negative ions surround each other. Si 4+ and O 2-

Enthalpy heat of reaction and change in enthalpy are used interchangeably for a reaction at constant Pressure ∆H = H products - H reactants endothermic: + ∆Hexothermic: - ∆H Reactants Products 2H 2 + O 2  2 H 2 O

+ -

Effects of a Catalyst on Activation Energy The catalyst speeds up the reaction by lowering the activation energy. Which graph is Exothermic? A B Which is Endothermic? In which graph is ΔH negative? In which graph is ΔH positive?

Energy Transfer Removing electrons uses energy (endothermic) ΔH = +495 kJ/mol Na kJ/mol  Na + + e - Adding electrons releases energy (exothermic) ΔH = -349 kJ/mol Cl + e -  Cl kJ/mol Salt formation releases energy (exothermic) ΔH = -411 kJ/mol Na + + Cl -  NaCl kJ/mol The net energy transfer determines if the overall reaction enthalpy (ΔH) is exo- or endothermic. ΔH rxn = H products - H reactants = (-349 kJ/mol kJ/mol) kJ/mol = kJ/mol (Remember: “Making Sodium Chloride” video)

Properties of Salts High melting points and boiling points. Solid salts do not conduct electricity. Salt solutions are good conductors of electricity. CTD – Conductivity, temperature, depth

Ionic Nomenclature: Monoatomic Ions It’s easy, just name the positive ion first and then the negative ion, but change the negative ions last three letters to –ide. If more than one ion exists for a metal, use a roman numeral to show which one. Examples: 1) NaCl = 2) CaF 2 = 3) Fe 2 O 3 = 4) PbO = sodium chloride calcium fluoride iron (III) oxide lead (II) oxide Hint: Look at the opposite (negative) ion to determine Roman numeral of transition metals.

Predicting Salt Formulas – The Crossing Rule Steps: 1.Look up ion charges (periodic table) 2.Switch the numbers and drop the charges 3.Reduce if possible aluminum oxide Salts are neutral so think: Balance the charges!!

You Try 1.What is the formula of zinc bromide? 2.What is the formula of copper (II) oxide? 3.What is the formula of copper (I) oxide? 4.What is the formula of Tin (IV) sulfide? ZnBr 2 CuO SnS 2 Cu 2 O

Ionic Nomenclature: Polyatomic Ions Some groups of covalently bonded atoms act as ions, many of which are negative (see the back of your periodic table for a list of ions and the names). Name them just like the monoatomic ions using the names from the back of the periodic table. Example: SeO 4 2- = selenate, so: K 2 SeO 4 = potassium selenate

You Try 1.NaNO 3 = 2.Ca 3 (PO 4 ) 2 = 3.Pb 3 (C 6 H 5 O 7 ) 4 = sodium nitrate calcium phosphate lead (IV) citrate

The crossing rule and Polyatomic Ions Hint: use parenthesis to separate numbers

You Try 1.Lithium thiosulfate 2.Ammonium phosphate 3.Bismuth (III) dichromate Li 2 S 2 O 3 (NH 4 ) 3 PO 4 Bi 2 (Cr 2 O 7 ) 3

Silicates Rocks containing crystalline materials are called minerals. Silicates are a class of mineral whose anions contain silicon and oxygen, such as Si 4 O found in Mg 3 (Si 4 O 12 ) 2 Silicates make up much of the Earth’s crust.

Hydrates Hydrates are salts with water bonded into their formula. Hygroscopic means to absorb water. Anhydrous means the salt without the water. Learn the following prefixes (very important): PrefixNumber Value Hemi-½ Mono-1 Di-2 Tri-3 Tetra-4 Penta-5 Hexa-6 Hepta-7 Octa-8 Nona-9 Deca-10 Doci-12

Hydrate Nomenclature and Formulas The name of the salt is followed by a prefix for how much water and the word “hydrate.” Ex. BaCl 2. 2H 2 O = Use the crossing rule the same as before and then “add” the water indicated to write the formula from the name. Ex. Iron (III) nitrate nonahydrate = barium chloride dihydrate Fe(NO 3 ) 3. 9H 2 0

You Try Name: 1.(NH 4 ) 2 C 2 O 4. H CoCl 2. 6H 2 0 Give the correct formula 3. Sodium acetate trihydrate 4. Barium hydroxide octahydrate NaC 2 H 3 O 2. 3H 2 0 Ba(OH) 2. 8H 2 0 Ammonium oxalate monohydrate Cobalt (II) chloride hexahydrate

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