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Ionic and Covalent Bonds

Ionic and Covalent Bonds. Ionic Bonds. When an atom has less than 8 valence electrons in its outer shell, it will gain or lose electrons to become more stable. First outer shell = full with 2 valence electrons Every other shell = full with 8 valence electrons . Ionic Bonds.

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Ionic and Covalent Bonds

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  1. Ionic and Covalent Bonds

  2. Ionic Bonds • When an atom has less than 8 valence electrons in its outer shell, it will gain or lose electrons to become more stable. • First outer shell = full with 2 valence electrons • Every other shell = full with 8 valence electrons

  3. Ionic Bonds • When an atom loses an electron, it loses a negative charge and becomes a positive ion or Cation

  4. Ionic Bonds • When an atom gains a negative charge, it becomes a negative ion or Anion

  5. Ionic Bond • When the two bonds come together, the opposite charges cancel out • Find the charge by locating the element in the group (column) on the periodic table • Ex. Group 1 has 1 valence electron, can easily give it away to form a complete outer shell • Na has an oxidation number of 1+ (left with a positive charge after giving away its valence electron)

  6. Ionic Bond Ex. Group 17 has 7 valence electrons, can easily gain 1 more to have a full outer shell - Cl has an oxidation number of 1- because it gains a negative charge when it completes it’s outer shell Ionic Bond between Na and Cl: Na1+Cl1-  NaCl

  7. Ionic Bonds • Polyatomic Ions- ions that are made of more than one atom Ex. Carbonate ion (CO32-) can bond with another ion of an opposite charge, Ca2+ _charges cancel out, forming CaCO3

  8. Naming Ionic Compounds • For an ionic compound, the name of the positive ion comes first, followed by the name of the negative ion • If the negative ion is an element, the end of its name changes to –ide • Ex. Mg2+O2- MgO Use the names of the elements and change the 2nd element’s ending to –ide Magnesium oxide

  9. Naming Polyatomic Ions • If the negative ion is polyatomic, its name remains unchanged. • Ex. Baking Soda NaHCO3 Sodium carbonate -Usually use the first two elements and change the second element’s ending to -ate

  10. Covalent Bonds • Chemical bonds formed between 2 or more nonmetals • 2 or more atoms share electrons at the same time

  11. Covalent Bonds • To form a covalent bond, find the number of valence electrons that each element has (group #) • Determine how each element can share valence electrons in order to form a full outer shell

  12. Covalent Bonds • Ex. Carbon dioxide C has 4 valence electrons, needs to gain 4 O has 6 valence electrons, needs to gain 2

  13. Covalent Bonds Ex. Cl has 7 valence electrons, bonds with another Cl to share 1 valence electron. Each atoms now has a full outer shell (8). 1 pair of shared valence electrons: Cl - Cl ; Cl2

  14. Covalent Bonds • Double bonds- two pairs of electrons are shared between atoms

  15. Covalent Bonds • Molecular Compounds- consist of molecules having covalently bonded atoms

  16. Covalent Bonds • Some atoms pull more strongly on the shared electrons that other atoms do. As a result, the electrons move closer to one atom, causing the atoms to have slight electrical charges. • Polar- a covalent bond in which electrons are shared unequally Ex.

  17. Covalent Bonds • Nonpolar- the valence electrons are shared equally in a covalent bond Ex.

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