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Understanding the Periodic Table: Properties and Trends

Explore the history, organization, and key concepts of the periodic table, including elements, groups, series, and trends in atomic radii and reactivity. Understand how electron configurations influence properties.

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Understanding the Periodic Table: Properties and Trends

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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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