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Chapter 5

Chapter 5. Periodic Trends. Dimitri Mendeleev. Organized first Periodic Table Based on increasing atomic mass and properties Left gaps for non-discovered elements. Moseley. Concept of atomic number Atomic number= number of protons. Periodic Law.

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Chapter 5

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  1. Chapter 5 Periodic Trends

  2. Dimitri Mendeleev • Organized first Periodic Table • Based on increasing atomic mass and properties • Left gaps for non-discovered elements

  3. Moseley • Concept of atomic number • Atomic number= number of protons

  4. Periodic Law • When elements are arranged in increasing atomic number their physical and chemical properties show a pattern

  5. Modern Periodic Table • Based on Atomic number and properties

  6. Group1- Alkali Metals • Group 2- Alkaline Earth Metals • Group 17- Halogens • Group 18- Noble Gases

  7. Lanthanide Series • Actinide Series

  8. Metals • Luster or shine • Conductors • Solids (usually) • Malleable (can be pounded) • Ductile (can be drawn into wires)

  9. Nonmetals • Poor conductors • Most are gases • Variation of physical properties

  10. Metalloids • Semi-metals • Properties of metals and nonmetals

  11. Periodic Trends • Properties of elements can be predicted (trend)

  12. Atomic Radius • Size of the radius of the atom • Across the period- • Down the Group

  13. Examples

  14. Ionic Radius • Size of the ion compared to the neutral atom

  15. Positive ions are smaller than neutral ions • More protons than electrons greater attraction

  16. Negative ions are larger than neutral ions • More electrons than protons less attraction

  17. Ionization Energy • Energy needed to remove an electron • High I.E.  strong attraction • Low I.E.  weak attraction

  18. Across the period: • Down the group:

  19. Successive ionization energies • Energy increase with each electron removed from an atom, but a jump will occur when the valence electrons are all removed

  20. examples

  21. Electron Affinity • Energy change that occurs when an atom gains an extra electron. • Atoms that have a greater attraction for electrons have a more negative affinity

  22. examples

  23. Electronegativity • Ability to attract an electron

  24. Fluorine is the most attractive. • Fluorine’s electronegativity was assigned 4.0 • All elements are compared to Fluorine

  25. Across the Period • Down the Group

  26. Octet Rule • Atoms tend to gain, lose or share electrons in order to acquire an octet. • Metals: gain or lose electrons? • Nonmetals: gain or lose electrons?

  27. Can Hydrogen ever acquire an octet? • Why are Noble Gases unreactive?

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