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IONS

IONS. Objectives: The Student will… Determine the # of valence electrons & ionic charge of a representative element. Explain how ion formation follows the octet rule. Model cation & anion formation. Make use of an Ion Reference Sheet. Octet Rule.

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IONS

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  1. IONS

  2. Objectives: The Student will… • Determine the # of valence electrons & ionic charge of a representative element. • Explain how ion formation follows the octet rule. • Model cation & anion formation. • Make use of an Ion Reference Sheet

  3. Octet Rule • In forming compounds, atoms tend to achieve the electron configuration of a noble gas. • An octet is a set of eight. • Each Noble gas, except for He, has 8 electrons in its valence shell and a configuration of: n s2 n p6

  4. Octet Rule • Atoms of Metals tend to losetheir valence electrons, leaving a complete octet in the next energy level down. • Non – metals tend to gain electrons or to share electrons with another non-metal to achieve a complete octet

  5. IONS • An atom is electrically neutral because # protons = # electrons • An ION forms when an atom or a group of atoms lose or gain electrons. • An Ion is NOT electrically Neutral

  6. Formation of Cations • An atom’s loss of valence electrons produces a cation, or a positively charged ion. • Metals form cations Na : 1s22s22p63s1 ATOM Na+1 : 1s22s22p6 ION • The e- configuration of the sodium ion is the same as that of a neon atom (#10)

  7. Formation of Anions • An atom’s gain of valence electrons produces an anion, or a negatively charged ion. • Non - metals form anions O : 1s22s22p4 ATOM O-2 : 1s22s22p6 ION • The e- configuration of the oxygen ion is the same as that of a neon atom (#10)

  8. Ions of the Representative Elements • Family 1A, alkali metals, have 1 valence electron. • To obey the octet rule, every element of this family will lose the 1 valence e- and become a cation with a +1 charge. • Li +1 Na +1 K+1 Rb +1 Cs +1 Fr+1

  9. Ions of the Representative Elements • Family 2A, alkaline earth metals, have 2 val. e-. This family produces cations with a +2 charge. • Family3A, boron’s family, produces +3 cations • Family 4A, carbon’s family, will produce +4 cations **Things change a little bit once we reach family 5A**

  10. Ions of the Representative Elements • Family 5A, Nitrogen’s family, has 5 valence electrons. Will it be easier for this family to lose 5 electrons to achieve an octet? Or gain 3 electrons to achieve an octet?

  11. Ions of the Representative elements • Family 5A will gain 3 electrons to achieve an octet. • If an atom gains electrons it becomes an anion; anions are negatively charged. • Family 5A, anions with -3 charge. N-3 , P-3, As-3, …

  12. Ions of the Representative Elements Family 6A: Family 7A, the Halogens: Family 8A, the Noble gases:

  13. Polyatomic Ions • Polyatomic ions are composed of more than one type of atom/element. • Tightly bound groups of atoms that behave as a unit and carry a charge. Examples: SO4-2 PO4-3 MnO4-1 C2H3O2-1

  14. Ion Reference Sheet

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