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Chemical bonding

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A quick overview of chemical bonding!

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Chemical bonding

  1. 1. Chemical Bonding: Ionic, Covalent, and Metallic By: Sakina Haji Pd. 6
  2. 2. What is a Chemical Bond? A chemical bond holds two atoms together. It is formed by the attraction of a positive and a negative ion or by the attraction of a positive nucleus to negative electrons. Atoms form chemical bonds to get eight valence electrons, to complete the octet rule and to become stable. 3 types: Ionic, Covalent, and Metallic
  3. 3. Ionic Bonds Ionic bonds form between cations (metals) and anions (nonmetals). The metal transfers its valence electron to the nonmetal. The nonmetal accepts the valence electrons and turns into a negative ion, while the metal becomes a positive ion. Arranged in a pattern of a crystal lattice High melting and boiling points Hard, rigid, and brittle
  4. 4. Ionic Bonds: Energy The formation of ionic compounds is exothermic. The energy required to separate ions is called the lattice energy. The more negative the lattice energy, the stronger the force of attraction. Lattice energy of smaller compounds is more negative than that of larger compounds because the nucleus holds the valence electrons more closely together.
  5. 5. Covalent Bonds Instead of transferring electrons, atoms share electrons. If one pair of electrons are shared, a single bond is formed (Group 17 elements form single bonds). If multiple pairs of electrons are shared, double and triple bonds can be formed (carbon, nitrogen, oxygen, and sulfur usually form multiple bonds).
  6. 6. Covalent Bonds: Sigma vs. Pi Single covalent bonds are called sigma bonds. Occurs when the electron pair is shared in an area centered between the two atoms. A sigma bond results if the valence atomic orbitals overlap end to end. A pi bond is formed when parallel orbitals overlap to share electrons. The shared electron pair occupies the space above and below the place where the atoms are joined. A double bond has one sigma and one pi bond. A triple bond has one sigma bond and two pi bonds.
  7. 7. Covalent Bonds: Energy Bond length: Distance between the atoms Bond dissociation energy: Amount of energy required to bread a covalent bond The smaller the bond length, the greater the bond dissociation energy, and vice versa.
  8. 8. Covalent vs. Ionic
  9. 9. Metallic Bonds When metals bond together to complete the octet rule. All metal atoms contribute their valence electrons to form a sea of electrons. Electrons are free to move b/w the atoms.
  10. 10. Metallic Bonding: Alloys An alloy is a mixture of elements that has metallic properties. Properties of alloys are different from those of the elements in it. Alloys most commonly forms when elements involved are similar in size or the atoms of one element are considerably smaller than the atoms of the other. There are two types of alloys, substitutional and interstitial.
  11. 11. Metallic Bonds: Energy Metallic bonds are weak and little energy is needed to break the bonds. Therefore, they have high melting points Because the electrons are mobile, they transfer heat more efficiently and, therefore, are better conductors.
  12. 12. Conclusion Elements bond to become stable. Elements bond to have 8 valence electrons. 3 types of bonds: Ionic, Covalent, Metallic In ionic bonds, one element gives its electrons to another element. Covalent bonds are the strongest bonds. Elements share electrons. Metallic bonds are the weakest bonds. Elements are in a sea of electrons

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