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Chemical bonding
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Chemical bonding

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  • 1. Chemical Bonding 2. When two or more atoms are joined, chemical compounds are formed. 3. When the combination’s total energy is lower than the energy of the separated atoms, a stable compound occurs.
  • 1. The two extreme cases of chemical bonds are covalent bonds and ionic bonds. 2. When one or more pairs of electrons are shared by two atoms, a covalent bond is created. 3. An ionic bond is a bond in which one or more electrons from an atom are removed and attached to another atom, resulting in positive and negative ions which attract eachother. 4.
  • 1. Other Types of Bonds 2. Metallic bonding is the electrostatic attraction between delocalized electrons, called conduction electrons, and the metallic ions within metals. 3. This type of force always involves a hydrogen atom and the energy of this attraction is close to that of weak covalent bonds (155 kJ/mol), thus the name - Hydrogen Bonding.
  • How are Ionic Bonds formed? 1. Elements from opposite ends of the periodic table will usually form ionic bonds.
  • 1. Properties of Ionic Compounds. 2. They are chrystalline solids, which means they are made of ions. 3. They have high melting and boiling points. 4. They are good conductors of electricity when they are melted. 5. Many ionic compounds are soluble in water, but not in nonpolar liquid.
  • How are covalent bonds formed? Elements which are close together in electronegativity tend to form covalent bonds and can exist as stable free molecules. An example is carbon dioxide.
  • The first subtype of covalent bonding. It is a nonpolar bond. H2 is a common example. The bonding electrons are equally shared by the two atoms, and a nonpolar covalent bond is formed.
  • The second subtype of covalent bonding. It’s a polar bond. These bonds are formed when electrons are unequally shared between two atoms. An example is the hydrogen-oxygen bond in the water molecule.
  • Properties of covalent compounds. They are always gases, liquids, or solids made of molecules. They have low melting and boiling points. Covalent compounds are poor electrical conductors in all phases. Many are soluble in nonpolar liquids, but not in water.
  • Coordinate covalent bonds. These are covalent bonds in which both of the electrons in the shared pair come from the same atom. Covalent bonds don’t lose of gain electrons. The 2 bonded atoms vibrate back and forth. The average distance that separates them is known as their bond length, and energy levels are inversely related. Electrons are not shared equally.
  • 1. Ionic and covalent, 2. No, 3. to form a stable compound

Transcript

  • 1. Chemical BondingChemical BondingPresented by:Presented by:Gulfam HussainGulfam Hussain
  • 2. Chemical BondingChemical Bonding►Chemical compounds are formed by theChemical compounds are formed by thejoining of two or more atoms.joining of two or more atoms.►►A stable compound occurs when the totalA stable compound occurs when the totalenergy of the combination has lower energyenergy of the combination has lower energythan the separated atoms.than the separated atoms.
  • 3. The two extreme cases of chemicalThe two extreme cases of chemicalbonds are:bonds are: Covalent bond: bond inCovalent bond: bond inwhich one or more pairs ofwhich one or more pairs ofelectrons are shared by twoelectrons are shared by twoatoms.atoms. Ionic bond: bond in whichIonic bond: bond in whichone or more electrons fromone or more electrons fromone atom are removed andone atom are removed andattached to another atom.attached to another atom.
  • 4. Other Types of Bonds Metallic Bonds:In metals all atoms loses their valenceelectrons which form electronic cloud , whichattracts the nucleus of neighboring atoms. Hydrogen Bonding:Electrostatic force of attraction between highlyelectronegative atom and partially positivehydrogen atom e.g water.
  • 5. Ionic Bond An ionic bond  is a type of chemical bond formed through an electrostatic attraction between two oppositely charged ions. Ionic bonds are formed between a cat ion, which is usually a metal, and an anion, which is usually a nonmetal. Example: NaCl forms ionic bond.
  • 6. How are Ionic Bonds Formed?How are Ionic Bonds Formed? Elements from opposite ends of theElements from opposite ends of theperiodic table will generally form ionicperiodic table will generally form ionicbonds.bonds.
  • 7. Properties of Ionic CompoundsProperties of Ionic Compounds Crystalline solidsCrystalline solids High melting and boiling pointsHigh melting and boiling points Conduct electricity when meltedConduct electricity when melted Many soluble in water but not in nonpolarMany soluble in water but not in nonpolarliquidliquid
  • 8. Covalent BondsCovalent Bondsbond in which one or more pairs ofbond in which one or more pairs ofelectrons are shared by two atoms.electrons are shared by two atoms.The atoms in covalent bonds do notThe atoms in covalent bonds do notlose or gain electrons, insteadlose or gain electrons, insteadThey share pairs of electrons toThey share pairs of electrons toachieve stability, often by fillingachieve stability, often by fillingtheir outer energy levels totheir outer energy levels toachieve an octet.achieve an octet.Example: N2 forms covalent bond.Example: N2 forms covalent bond.
  • 9. How are Covalent Bonds Formed? Elements which are close together inelectronegativity tend to form covalent bondsand can exist as stable free molecules. Carbon dioxide is a common example.
  • 10. First Subtype of CovalentFirst Subtype of CovalentBondingBonding Nonpolar bondNonpolar bond Example: HExample: H2 Because both atoms in the HBecause both atoms in the H2 moleculemoleculehave an equal attraction (or affinity) forhave an equal attraction (or affinity) forelectrons, the bonding electrons areelectrons, the bonding electrons areequally shared by the two atoms, and aequally shared by the two atoms, and anonpolar covalent bond is formed.nonpolar covalent bond is formed.
  • 11. Second Subtype of CovalentSecond Subtype of CovalentBondingBonding• Polar Bond• formed when electrons are unequallyshared between two atoms• Example: the hydrogen-oxygen bond inthe water molecule.
  • 12. Properties of CovalentProperties of CovalentCompoundsCompounds• Gases, liquids, or solids• Low melting and boiling points• Poor electrical conductors in all phases• Many soluble in non polar liquids but not inwater• Are brittle• When 2 atoms bond covalently theresulting particle is a molecule
  • 13. Coordinate CovalentCoordinate CovalentBondsBonds Covalent bonds in which both of the electronsCovalent bonds in which both of the electronsin the shared pair come from the same atomin the shared pair come from the same atom Covalent bonds don’t lose or gain electronsCovalent bonds don’t lose or gain electrons Electrons are not shared equallyElectrons are not shared equallyExample:Example:The bond between NH3 and BF3 isThe bond between NH3 and BF3 is CoordinateCoordinateCovalent BondsCovalent Bonds
  • 14. What Have You Learned?What Have You Learned? What are the two extreme casesWhat are the two extreme casesof bonds?of bonds? Do covalent bonds lose or gainDo covalent bonds lose or gainelectrons? (Yes or No).electrons? (Yes or No). Why do atoms bond?Why do atoms bond?
  • 15. AnyAnyQuestionQuestion??