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The Periodic Table & Formation of Ions

The Periodic Table & Formation of Ions. Development of the Periodic Table. Mendeleev: Considered to be the father of the periodic table Arranged elements by increasing atomic mass Placed elements with similar properties in columns Left blank spaces for undiscovered elements

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The Periodic Table & Formation of Ions

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  1. The Periodic Table & Formation of Ions

  2. Development of the Periodic Table • Mendeleev: • Considered to be the father of the periodic table • Arranged elements by increasing atomic mass • Placed elements with similar properties in columns • Left blank spaces for undiscovered elements • Was able to accurately predict properties of the undiscovered elements

  3. The Modern Periodic Table • Moseley • Arranged elements by increasing atomic number • Gave a clearer pattern of periodic properties • Periodic Law: there is a periodic repetition of chemical and physical properties of elements when they are arranged by increasing atomic number

  4. Arrangement of the table • Groups/Families • Columns of elements • Numbered 1 to 18 • Elements have similar properties • Elements have the same # of valence electrons • Periods • Rows of elements • Numbered 1 to 7 • Corresponds to number of energy levels of an atom

  5. Groups with Special Names • Group 1: • Alkali Metals • Group 2: • Alkaline Earth Metals • Groups 3 -12: • Transition Metals • Group 17 • Halogens • Group 18 • Noble Gases

  6. Each group contains elements with the same number of valence electrons

  7. Example 1 • Without drawing electron configurations, determine the number of valence electrons for each of the following: • A. Calcium • B. Neon • C. Sodium • D. Aluminum • E. Sulfur

  8. Periodic Trends Valence electrons Atomic Radius Ionization Energy: Energy required to remove an electron from a neutral atom Electronegativity: The attraction of an atom for shared electrons in a covalent bond

  9. Atomic Radius Increases from top to bottom in a group Decreases from left to right across a period

  10. Example 2 • Arrange each of the following in order of increasing atomic radius (smallest  largest) • A. Calcium, Magnesium, Barium • B. Fluorine, Iodine, Chlorine • C. Calcium, Arsenic, Bromine • D. Chlorine, Fluorine, Oxygen

  11. Ionization Energy Increases from left to right across a period Decreases from top to bottom in a group

  12. Example 3 • Place the following in order of increasing ionization energy (lowest  highest) • A. Sulfur, Oxygen, Selenium • B. Calcium, Magnesium, Beryllium • C. Lithium, Fluorine, Nitrogen • D. Carbon, Silicon, Nitrogen

  13. Electronegatvity Increases from left to right across a period Decreases from top to bottom in a group

  14. Example 4 • Determine the most electronegative element in each pair • A. Calcium, sulfur • B. sulfur, chlorine • C. potassium, bromine • D. Silicon, phosphorus

  15. Octet Rule • Typically, elements want to have 8 valence electrons (except hydrogen and helium) in order to be stable • Noble gases are stable because they have 8 valence electrons • Other elements will lose, gain, or share electrons in order to have 8 valence

  16. Becoming Stable • Remember atoms are neutral because they have equal #’s of protons and electrons • When an atom gains or loses electrons, this equality is upset… • The atom is no longer neutral…and is no longer called an atom

  17. Ions • An ion is an atom that has an electric charge because it has lost or gained electrons • If an atom loses electrons, its charge will become positive. It is called a cation. • If an atom gains electrons, its charge will become negative. It is called an anion.

  18. On the Periodic Table

  19. Ionic Charges • The number of electrons that an atom will gain or lose in order to become stable determines its ionic charge • Metals lose electrons and have + charge (These are called cations) • Nonmetals gain electrons and have – charge (These are called anions)

  20. Size of Ions Cations (+ charges) are smaller than their parent atoms Anions (- charges) are larger than their parent atoms

  21. Example 5 • Determine the ionic charge for each of the following. Indicate if it is a cation or an anion: • A. Magnesium • B. Chlorine • C. Oxygen • D. Sodium • E. Nitrogen

  22. Naming Ions • If the ion is positive…name it the atom’s name followed by the word ion • Example: Sodium is Na1+…its name is Sodium ion • If the ion is negative…change the atom’s name to have an –ide ending then write the word ion • Example: Chlorine is Cl1-…its name is chloride ion

  23. Example 6 • Indicate the ionic charge and the name of the ion formed from each of the following elements: • A. Potassium • B. Bromine • C. Aluminum • D. Cesium • E. Fluorine

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