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Chemical Bonding

- Valence Electrons - Bonding - Formulas and Nomenclature - Chemical Reactions - Oxidation States. Chemical Bonding. Electrons. Atomic number = number of electrons Electrons orbit around the nucleus The nucleus consists of Protons and Neutrons Electrons determine how atoms behave….

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Chemical Bonding

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  1. - Valence Electrons - Bonding - Formulas and Nomenclature - Chemical Reactions - Oxidation States Chemical Bonding

  2. Electrons • Atomic number = number of electrons • Electrons orbit around the nucleus • The nucleus consists of Protons and Neutrons • Electrons determine how atoms behave…

  3. Electrons orbit in shells… • The 1st shell closest to the nucleus can hold 2 electrons • Every other shell can hold 8 electrons

  4. Octet Rule = atoms tend to gain, lose or share electrons so as to have 8 electrons • C would like to • N would like to • O would like to Gain 4 electrons Gain 3 electrons Gain 2 electrons

  5. Valence Electrons • These are the electrons in the outer most shell. • Valence electrons influence how an atom will bond.

  6. Electron Dot Diagrams • Show the valence electrons only.

  7. Learning Check  A. X would be the electron dot formula for 1) Na 2) K 3) Al   B.  X  would be the electron dot formula for  1) B 2) N 3) P

  8. Bonding Types • Ionic Bonding • Covalent Bonding • Metallic Bonding

  9. Ionic Bonds • Formed by a transfer of electrons • Formed between a metal and a nonmetal • Metals loseelectrons to match the number of valence electrons of their nearest noble gas • Nonmetals gain electrons to match the number of valence electrons of their nearest noble gas

  10. Ionic Bonding • All atoms are electrically neutral until electrons are transferred. • When electrons are transferred, ions form… • When an atom gains an electron, it will gain a negative charge. • When an atom loses an electron, it will gain a positive charge. • A positive ion is called a cation. • A negative ion is called an anion.

  11. How to Calculate Ionic Charges…

  12. What are the charges if the following atoms became ions? • Ca  • N  • I  • Na  • Ba • Ar • C  • Ca 2+ , N 3- , I - , Na + , Ba2+ , Ar (no charge), C 4+ or C 4-

  13. Ionic Bonding • What makes ionic bonding work? • When electrons are transferred, the charge difference causes an attraction between the ions.

  14. Covalent Bonds • Formed from sharing of electrons. • Formed between 2 nonmetal atoms.

  15. Diatomic Elements • All diatomic elements share electrons covalently. • Brinclhof • Br. I. N. Cl. H. O. F. • Br2, I2, N2, Cl2, H2, O2, F2

  16. Electronegativy • An atoms ability to attract electrons.

  17. Polar Covalent Bonds and Non-Polar Covalent Bonds • Polar Covalent Bonds – When electrons are NOT shared equally. • Causes dipoles and partially charged atoms. • Symbols for partial charges =

  18. Polar or Non-Polar Covalent Bond? • Ionic Bond - If the difference of electronegativity between two bonded atoms is greater than 2. • Polar Covalent Bond – If the difference of electronegativity between two bonded atoms is between 2 and 0.41. • Non-Polar Covalent Bond – If the difference of electronegativity between two bonded atoms is less than 0.40.

  19. Polar or Non-Polar Covalent Bond? • Label the following as having polar bonds or nonpolar bonds. • H20  • NH3 • CH4 • CO  • O2 • Answers: H20 – Polar, NH3 – Polar, CH4 – NonPolar, CO – Polar, O2 – NonPolar

  20. Metallic Bonds • Bond found in metals and holds metal atoms together very strongly • Metallic bonding constitutes the electrostatic attractive forces between the delocalized electrons, called conduction electrons, gathered in an electron cloud, and immersed in the positively charged metal ions.

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