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Covalent Bonds

Covalent Bonds. Coach Medford Building Science Champions . Objectives. Describe how covalent bonds form. Identify the properties of molecular compounds. Distinguish between polar and nonpolar bonds, and between polar and nonpolar compounds. Key Terms. Covalent bond Double bond

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Covalent Bonds

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  1. Covalent Bonds Coach Medford Building Science Champions

  2. Objectives • Describe how covalent bonds form. • Identify the properties of molecular compounds. • Distinguish between polar and nonpolar bonds, and between polar and nonpolar compounds.

  3. Key Terms • Covalent bond • Double bond • Molecular compound • Polar • Nonpolar

  4. Covalent Bond • Co = share valent = valence electrons = shared electrons • A covalent bond is a chemical bond formed when two atoms SHARE electrons. • Form between 2 or more nonmetals. • Oxygen, carbon, nitrogen and the halogen family frequently bond with other nonmetals by sharing electrons.

  5. Fluorine • F + F F F • Each fluorine has 7 valence electrons • They share 1 pair • When you count the valence electrons, you count the shared pair each time. • By sharing they have 8 valence electrons. • In a covalent bond, both atoms attract the 2 shared electrons at the same time. Shared pair of electrons

  6. Number of Bonds • There are 3 types of pairing for covalent bonds: • Single Bond – shares one pair of electrons • Double Bond – shares two pairs of electrons • Triple Bond – shares three pairs of electrons F F O O N N Single Bond Double Bond Triple Bond

  7. Molecular Compounds Properties Melting and Boiling Points of Molecular Compounds • Molecular Compounds consist of molecules having covalently bonded atoms. • Weaker bonds than ionic bonds • Poor conductors of electricity • No charged particles • Used for insulation: ie. rubber and plastic *Carbon Dioxide changes from a solid to a gas

  8. Sharing of Electrons Polar Nonpolar • A covalent bond where electrons are not shared equally. H O H Pull is toward oxygen = Polar • A covalent bond where electrons are shared equally. F Cl Pull in opposite directions = nonpolar + - +

  9. Unequal Sharing of Electrons • Some atoms pull more strongly on the shared electrons than other atoms do. As a result, the electrons move closer to one atom, causing the atoms to have a slight electrical charge. • One electron is being pulled closer to one atom causing the atom losing an electron to become slightly positive and the one receiving an electron is slightly negative.

  10. Review • Valence electrons are shared between covalent bonds • Electrons are rapidly moving from one atom to another giving an atom a slight positive or negative charge

  11. Your Turn • Draw dot diagrams for the following compounds and write if they are Ionic or Covalent. IF THEY ARE COVALENT WRITE IF THEY ARE polar or nonpolar and what number bond they have. • N2 MgOCO2 • O2 NaClCaS • RbI NH3 CH4 • Al2O3 Higher difficulty

  12. References • Anderson, M. et all (2012) Physical Science. McGraw-Hill: Columbus • Frank, D.V et al (2001). Physical Science. Prentice Hall: New Jersey

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