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PSC Chap. 4

PSC Chap. 4. The Periodic Table. In modern periodic table, elements in the same column have similar properties. John Newlands - Law of Octaves. arranged first 16 elements in order of atomic mass found that similar properties were found every 8 th element.

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PSC Chap. 4

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  1. PSC Chap. 4 The Periodic Table

  2. In modern periodic table, elements in the same column have similar properties.

  3. John Newlands - Law of Octaves • arranged first 16 elements in order of atomic mass • found that similar properties were found every 8th element

  4. Dmitri Mendeleev - invented the modern periodic system - basis of the modern periodic table • arranged all known elements in order of atomic mass • placed elements w/ similar properties in vertical columns

  5. A couple of problems w/ Mendeleev's table • Some elements did not fit into the right columns when put in order of atomic mass. If switched, they fit. • -ex. Te and I, Co and Ni

  6. A couple of problems w/ Mendeleev's table • In order to put some elements in the right column, gaps had to be left in his table. • He predicted elements would be discovered to fill the gaps • Also correctly predicted properties of these undiscovered elements

  7. Henry Mosely, using X-rays, discovered the atomic number of elements.

  8. When elements in Mendeleev's table were placed in order of atomic number, they fell into the right columns.

  9. Periodic Law • - the physical and chemical properties of elements are a periodic function of their atomic numbers

  10. Period or Series • elements that form a horizontal row in the periodic table • all elements in the same series have the same outer energy level

  11. Group or Family • elements that form a vertical column in the periodic table • elements in the same group have similar electron configurations • also have similar properties.

  12. Metals - left side of table good conductors of electricity and heat shiny malleable groups 1-12 and some of groups 13-16 Nonmetals - right side of table poor conductors of electricity and heat dull brittle some of groups 14 -16 and all of groups 17 & 18 Periodic Table can be divided into 2 regions

  13. Metalloids • Semiconductors (semi-metals) • Have properties of both metals and nonmetals • lie on dividing line • used to make transistors and computer chips

  14. Main-Group Elements • Also called representative elements • s and p block elements • have consistent electron configurations

  15. Group 1 • Alkali Metals • all end in s1 • lose the outer e- to form +1 ions • Very reactive metals • React w/ water and oxygen • soft

  16. Group 2 • Alkaline Earth Metals • Active metals • end in s2 • lose 2 outer e-’s to form +2 ions • not as soft as group 1 metals

  17. Transition Metals • d block elements • highest energy e-’s are in the d sublevel • not as reactive as groups 1 and 2 • have varied properties

  18. Lanthanides and Actinides • f block elements • highest energy e-’s are in the f sublevel • sometimes called rare earth elements or inner-transition elements • Lanthanide series fills 4f sublevel • shiny, reactive, irregular configurations

  19. Lanthanides and Actinides • Actinide series fills 5f sublevel • radioactive

  20. Group 16 • Chalcogens • Contains active nonmetals (top) to metalloids to less active metals • end in s2p4 • nonmetals gain 2 e-’s to form -2 ions

  21. Group 17 • Halogens • Most reactive nonmetals • react with metals to form salts • end in s2p5 • gain 1 e- to form -1 ions

  22. Group 18 • Noble Gases • Mostly unreactive • end in s2p6

  23. Hydrogen • In a class by itself • Behaves unlike other elements because it has only 1 p+ and 1 e- • Most common element in the universe

  24. Properties of elements are determined by their electron configurations. • Elements with similar properties have similar electron configurations.

  25. Periodic Trends • Atomic radii • Reactivity

  26. Atomic radius • Atomic radius increases as you move down a group • Add an energy level as you move down • Atomic radius decreases as you move across a period • Increased nuclear charge pulls e- cloud in tighter

  27. Reactivity of Metals • Metals tend to lose e-’s • As you move down a group, reactivity of metals increases • Atoms are bigger and e-’s are held less tightly • As you move to the left, reactivity of metals increases • atoms are bigger to the left

  28. Reactivity of Metals • The most active metal is in the lower left corner of the periodic table. • Fr

  29. Reactivity of Nonmetals • Nonmetals tend to gain e-’s • As you move up a group, reactivity of nonmetals increases • Atoms are smaller and hold e-’s more tightly • As you move to the right, reactivity of nonmetals increases (noble gases not considered) • Atoms are smaller

  30. Reactivity of Nonmetals • The most active nonmetal is in the upper right corner of the periodic table. • F

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