Presentation on theme: "Chemical Bonding and Nomenclature"— Presentation transcript:
1 Chemical Bonding and Nomenclature By Paul SurkoNew Dimensions High SchoolPoinciana, FL
2 8 Chemical Bond I want you to meet a friend of mine? sChemicalBond8Bonding, the way atoms are attracted to 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.I want you to meet a friend of mine?
3 5.1 What are Molecules?Molecules are a combination of atoms bonded together. Bonding determines the chemical properties of the molecule (compound).
4 5.5 Ionic Bonding-Being Like the Noble Gases 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+2Al becomes Al+3Cl becomes Cl-O becomes O-2N becomes N-3The positive and negative ions are attracted to each other electrostatically.
7 5.2 The Covalent BondAtoms can form molecules by sharing electrons in the covalent bond. This is done only among non-metal atoms.
8 5. 3 Dot Structures-Octet Rule (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.
9 Rules to Write Dot Structures Write a skeleton molecule with the lone atom in the middle (Hydrogen can never be in the middle)Find the number of electrons needed (N) (8 x number of atoms, 2 x number of H atoms)Find the number of electrons you have (valence e-'s) (H)Subtract to find the number of bonding electrons (N-H=B)Subtract again to find the number of non-bonding electrons (H-B=NB)Insert minimum number of bonding electrons in the skeleton between atoms only. Add more bonding if needed until you have B bonding electrons.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.
10 Let's Try it! H O H S Water H2O N BNBEWater H2O2 x 2 = 4 for Hydrogen 1 x 8 = 8 for Oxygen 4+8=12 needed electrons12 N-8 H2 x 1 = 2 for Hydrogen 1 x 6 = 6 for Oxygen You have 8 available electrons-4 B4 NB= 4 bonding electronsH:O:H8 – 4 = 4 non-bonding electrons..H:O:H ●●..H:O:H ●●
11 Let's Try it! H H N H S Ammonia NH3 N BNBEAmmonia NH33 x 2 = 6 for Hydrogen 1 x 8 = 8 for Nitrogen 6+8=14 needed electrons14 N-8 H3 x 1 = 3 for Hydrogen 1 x 5 = 5 for Nitrogen You have 8 available electrons-6 B2 NB= 6 bonding electronsH.. H:N:H8 – 6 = 2 non-bonding electronsHH..H:N:H ●●..H:N:H ●●
12 Let's Try it! Carbon Dioxide CO2 S N H B NB E O C O 1 x 8 = 8 for Carbon 2 x 8 = 16 for Oxygen 8+16=24 needed electrons24 N-16 H1 x 4 = 4 for Carbon 2 x 6 = 12 for Oxygen You have 16 available electrons-8 B8 NB= 8 bonding electrons16 – 8 = 8 non-bonding electronsO::C::OO::C::O ●● ●●O::C::O ●● ●●
13 Let's Try it! O O C O Carbonate CO3-2 S N HBNBE3 x 8 = 24 for Oxygen 1 x 8 = 8 for Carbon 24+8=32 needed electrons32 N-24 H3 x 6 = 18 for Oxygen 1 x 4= 4 for Carbon You have more available e-'s-8 B16 NB= 8 bonding electronsO.. O::C:O24 – 8 = 16 non-bonding electrons.. :O:.. :O:O::C: O: ●● ●●-2O::C: O: ●● ●●
14 5.6 Polarity-Unequal Sharing of Electrons 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.
15 Examples of Polar and Non-Polar Compounds HCl The Chlorine wants the electrons more than the 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 ●● ●●HCO2 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.
16 5.7 Nomenclature Naming of Compounds Binary Compounds have two types of atoms (not diatomic which has only two atoms).Metals (Groups I, II, and III) and Non-MetalsMetal _________ + Non-Metal _________ideSodium Chlorine Sodium Chloride NaClMetals (Transition Metals) and Non-MetalsMetal ______ +Roman Numeral (__) + Non-Metal ________ideIron III Bromine Iron (III) Bromide FeBr3 Compare with Iron (II) Bromide FeBr2
17 5.7 Nomenclature Naming of Compounds Binary Compounds have two types of atoms (not diatomic which has only two atoms).Metals (Transition Metals) and Non-Metals Older SystemMetal (Latin) _______ + ous or ic + Non-Metal ________ideFerrous Bromine Ferrous Bromide FeBr2 Compare with Ferric Bromide FeBr3Non-Metals and Non-MetalsUse Prefixes such as mono, di, tri, tetra, penta, hexa, hepta, etc.CO2 Carbon dioxide CO Carbon monoxidePCl3 Phosphorus trichloride CCl4 Carbon tetrachlorideN2O5 Dinitrogen pentoxide CS2 Carbon disulfide
18 Let’s Practice! Name the following. CaF2 Calcium Flouride K2S Potassium SulfideCoI2Cobalt (II) Iodide or Cobaltous IodideSnF2Tin (II) Flouride or Stannous FlourideSnF4Tin (IV) Flouride or Stannic FlourideOF2Oxygen diflourideCuI2Copper (II) Iodide or Cupric IodideCuICopper (I) Iodide or Cuprous IodideSO2Sulfur dioxideSrSStrontium SulfideLithium BromideLiBr
19 Polyatomic Ions (partial list from page 195 (193 2nd edition)) Ammonium……………...Nitrate……………………Permanganate…………. .Chlorate…………………Hydroxide……………….Cyanide………………….Sulfate…………………...Carbonate……………….Chromate………………..Acetate…………………..Phosphate……………….NH4+NO3-MnO4-ClO3-OH-CN-SO4 2 -CO32-CrO42-C2H3O2-PO43-
20 Acids (with H in front) Binary acids (without oxygen in formula) Hydro _________ ic AcidHCl Hydrochloric acid HBr Hydrobromic acidOxy acids (with oxygen in formula)-ate goes to –ic and –ite goes to -ousHNO3 Nitric acid HNO2 Nitrous acidH2SO4 Sulfuric acid H2SO3 Sulfurous acidH3PO4 Phosphoric acid H3PO3 Phosphorous acid
21 Lets Practice! HF Hydroflouric acid Na2CO3 Sodium carbonate H2CO3 Carbonic acidKMnO4Potassium permanganateHClO4Perchloric acidH2SHyrdogen sulfuric acidNaOHSodium hydroxideCuSO4Copper (II) sulfate or Cupric sulfatePbCrO4Lead (II) chromate or Plubous chromateH2OHydrooxic acid (no……just water)NH3Nitrogen trihydride (no..just ammonia)