Chemical_Bonding_and_Nomenclature - Chemical Bonding and...

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Unformatted text preview: Chemical Bonding and Nomenclature and By Paul Surko New Dimensions High School Poinciana, FL s 8 Bonding, the to meet a are attracted to I want you way atoms friend of mine? each other to form molecules, determines nearly all of the chemical properties we see. And, as we shall see, the number “8” is very important to chemical bonding. 5.1 What are Molecules? 5.1 Molecules are a combination of atoms bonded together. Bonding determines the chemical properties of the molecule (compound). 5.5 Ionic Bonding-Being Like the Noble Gases the All atoms want to have the same number of electrons as the Noble Gases. The Noble Gases have very stable electron configurations. In order to achieve the same electron configuration as the Noble Gases metal atoms will give up electrons to form positive ions (cations) and non-metal atoms will receive or take additional electrons to become negative ions (anions). IONS are charged particles. Na becomes Na+ Mg becomes Mg+2 Al becomes Al+3 Cl becomes Cl- O becomes O-2 N becomes N-3 The positive and negative ions are attracted to each other electrostatically. Opposites Attract! Opposites Putting Ions Together Putting 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! MgF2 Li+ + Br- = LiBr Mg+2 + F- = Al+3 + I- = NH4+ + PO4-3 = (NH4)3PO4 Not NH43PO4 + K + Cl = KCl Sr+2 + P-3 = AlI3 S r 3 P2 5.2 The Covalent Bond 5.2 Atoms can form molecules by sharing Atoms electrons in the covalent bond. This is done only among non-metal atoms. only 5.3 Dot Structures-Octet Rule 5.3 (All atoms want 8 electrons around them.) Valence electrons are those in the outermost orbitals. They are the ones that can form bonds. Lewis came up with a way to draw valence electrons so that the bonding could be determined. Rules to Write Dot Structures Rules Write a skeleton molecule with the lone atom in the middle (Hydrogen can never be in the middle) (Hydrogen 2. Find the number of electrons needed (N) (8 x number of atoms, 2 x number of H atoms) (8 3. Find the number of electrons you have (valence e -'s) (H) Find 4. Subtract to find the number of bonding electrons (N-H=B) 5. Subtract again to find the number of non-bonding 5. electrons (H-B=NB) electrons 6. Insert minimum number of bonding electrons in the skeleton between atoms only. Add more bonding if needed until you have B bonding electrons. until 7. Insert needed non-bonding electrons around (not between) atoms so that all atoms have 8 electrons around them. The total should be the same as NB in 5 above. them. 1. 1.S 2.N 3.H 4.B 5.NB 6.E HOH Let's Try it! Let's Water H2O 2 x 2 = 4 for Hydrogen 1 x 8 = 8 for Oxygen 4+8=12 needed electrons 2 x 1 = 2 for Hydrogen 1 x 6 = 6 for Oxygen You have 8 available electrons 12 - 8 = 4 bonding electrons 8 – 4 = 4 non-bonding electrons .. H:O:H ●● 12 N - 8H - 4B 4 NB H:O:H .. H:O:H ●● 1.S 2.N 3.H 4.B 5.NB 6.E H HNH Let's Try it! Let's Ammonia NH3 3 x 2 = 6 for Hydrogen 1 x 8 = 8 for Nitrogen 6+8=14 needed electrons 3 x 1 = 3 for Hydrogen 1 x 5 = 5 for Nitrogen You have 8 available electrons 14 - 8 = 6 bonding electrons 8 – 6 = 2 non-bonding electrons H .. H:N:H ●● 14 N - 8H - 6B 2 NB H .. H:N:H H .. H:N:H ●● Let's Try it! Let's 1.S 2.N 3.H Carbon Dioxide CO2 OCO 1 x 8 = 8 for Carbon 2 x 8 = 16 for Oxygen 8+16=24 needed electrons 1 x 4 = 4 for Carbon 2 x 6 = 12 for Oxygen You have 16 available electrons 4.B 24 - 16 = 8 bonding electrons 5.NB 16 – 8 = 8 non-bonding electrons 6.E .. .. O::C::O ●● ●● 24 N - 16 H - 8B 8 NB O::C::O .. .. O::C::O ●● ●● 1.S 2.N 3.H Let's Try it! Let's O OCO Carbonate CO3-2 3 x 8 = 24 for Oxygen 1 x 8 = 8 for Carbon 24+8=32 needed electrons 3 x 6 = 18 for Oxygen 1 x 4= 4 for Carbon You have 22 + 2 more available e-'s 4.B 32 - 24 = 8 bonding electrons 5.NB 24 – 8 = 16 non-bonding electrons 6.E .. .. :O: .. .. O::C: O: ●● ●● -2 32 N - 24 H - 8B 16 NB O .. O::C:O .. .. :O: .. .. O::C: O: ●● ●● 5.6 Polarity-Unequal Sharing of Electrons of Even though all atoms want the same number of electrons as the Noble Gases, some want to get or give them more than others. The magnitude of this attraction for electrons is called “Electronegativity”. The more electronegative an atom is, the more it wants the electrons. Some atoms want to gain electrons so bad, they take them altogether to form negative ions. Some want to lose them so bad that they become positive ions. Examples of Polar and NonExamples Polar Compounds the HCl The Chlorine wants the electrons more than Hydrogen. Thus we have +δHCl-δ. NaCl Since Na is a metal it gives up its electron to form Na+ and Cl takes the electron completely to form Cl-. Cl2 (Cl—Cl) The Chlorine molecules want the electrons equally so they form a non-polar molecule with NO partial or full charges. H2O Water is a bent molecule. The lone pair of electrons from the Lewis structure distorts its shape and it becomes a very polar molecule. .. .. .. :O:H O::C::O ●● ●● ●● H CO2 Carbon Dioxide is a linear molecule. It has no lone pairs of electrons from the Lewis structure. The two oxygen atoms pull equally and make it a non-polar molecule. 5.7 Nomenclature 5.7 Naming of Compounds Binary Compounds have two types of atoms (not diatomic Binary which has only two atoms). Metals (Groups I, II, and III) and Non-Metals Metal _________ + Non-Metal _________ide Sodium Chlorine Sodium Chloride NaCl Metals (Transition Metals) and Non-Metals Metal ______ +Roman Numeral (__) + Non-Metal ________ide Iron III Bromine Iron (III) Bromide FeBr3 Compare with Iron (II) Bromide FeBr2 5.7 Nomenclature 5.7 Naming of Compounds Binary Compounds have two types of atoms (not diatomic Binary which has only two atoms). Metals (Transition Metals) and Non-Metals Older System Metal (Latin) _______ + ous or ic + Non-Metal ________ide Ferrous Bromine Ferrous Bromide FeBr2 Compare with Ferric Bromide FeBr3 Non-Metals and Non-Metals Use Prefixes such as mono, di, tri, tetra, penta, hexa, hepta, etc. CO2 Carbon dioxide CO Carbon monoxide PCl3 Phosphorus trichloride CCl4 Carbon tetrachloride N O Dinitrogen pentoxide CS Carbon disulfide Let’s Practice! Let’s Name the following. CaF2 K2S CoI2 SnF2 SnF4 OF2 CuI2 CuI SO2 SrS LiBr Calcium Flouride Potassium Sulfide Cobalt (II) Iodide or Cobaltous Iodide Tin (II) Flouride or Stannous Flouride Tin (IV) Flouride or Stannic Flouride Oxygen diflouride Copper (II) Iodide or Cupric Iodide Copper (I) Iodide or Cuprous Iodide Sulfur dioxide Strontium Sulfide Lithium Bromide Polyatomic Ions Polyatomic (partial list from page 195 (193 2nd edition)) Ammonium……………... Nitrate…………………… Permanganate…………. . Permanganate…………. Chlorate………………… Hydroxide………………. Cyanide…………………. Sulfate…………………... Carbonate………………. Chromate……………….. Acetate………………….. Phosphate………………. NH4+ NO3- MnO4- ClO3- OHCNSO4 2 - CO32- CrO42- C2H3O2- PO43- Acids (with H in front) (with Binary acids (without oxygen in formula) Hydro _________ ic Acid HCl Hydrochloric acid HBr Hydrobromic acid Oxy acids (with oxygen in formula) -ate goes to –ic and –ite goes to -ous HNO3 Nitric acid HNO2 Nitrous acid H2SO4 Sulfuric acid H2SO3 Sulfurous acid H3PO4 Phosphoric acid H3PO3 Phosphorous acid Lets Practice! Lets HF Na2CO3 H2CO3 KMnO4 HClO4 H2S NaOH CuSO4 PbCrO4 H2O NH3 Hydroflouric acid Sodium carbonate Carbonic acid Potassium permanganate Perchloric acid Hyrdogen sulfuric acid Sodium hydroxide Copper (II) sulfate or Cupric sulfate Lead (II) chromate or Plubous chromate Hydrooxic acid (no……just water) Nitrogen trihydride (no..just ammonia) ...
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This note was uploaded on 11/09/2011 for the course CHEM 100 taught by Professor Sdfsdf during the Winter '08 term at BYU.

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