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Periodicity

Objectives: AHSGE Reading 4.3 Discern organizational patterns. Other AOD C.3.2 Recognize periodic trends of elements, including the number of valence electrons, atomic size, and reactivity. Periodicity. Periodic Law.

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Periodicity

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  1. Objectives: AHSGE Reading 4.3 Discern organizational patterns. Other AOD C.3.2 Recognize periodic trends of elements, including the number of valence electrons, atomic size, and reactivity. Periodicity

  2. Periodic Law • Dmitri Mendeleev’s periodic table had the elements arranged in order of increasing mass. • There is a periodic repetition of chemical and physical properties of the elements when they are arranged by increasing atomic number

  3. Modern Periodic Table • What are the columns called? • Answer: Groups • What are the horizontal rows called? • Answer: Periods • Label groups & rows on your periodic table!!

  4. Modern Periodic Table • Representative elements: elements in the A groups (1A-8A) • “the main group” • Possess a wide range of physical and chemical properties • Transition elements: elements in the B groups (1B-8B)

  5. Metals • Describe some properties of metals. • Metals: • Generally shiny • Most are solid at room temperature • Good conductors of heat and electricity • Ductile and malleable • Most group A and all group B elements are metals.

  6. Groups 1A and 2A, EXCEPT HYROGEN, are metals. • The other elements in group 1A are called alkali metals. • Reactive & Readily combine with group 6 and 7 elements. • Group 2A elements are alkaline earth metals. • Contain a pair of electrons in their outermost shell.

  7. Both groups 1A and 2A are highly reactive (1A more so). • Why would group 1A be more reactive than group 2A? • Answer: Group 2A has a FILLED s orbital, but group 1A’s s orbital is only half-filled, so that electron is still looking for a partner to hook up with.

  8. Group B elements: • Transition metals: located on the main body of the periodic table • Inner transition metals: the 2 rows located along the bottom of the periodic table

  9. Nonmetals • Describe some properties of nonmetals. • Nonmetals: • Generally gases or brittle, dull-looking solids • Poor conductors of heat or electricity • The ONLY nonmetal that is a liquid at room temperature is bromine. • Located in the upper right portion of the periodic table

  10. Halogens: Group 7A elements; highly reactive • Noble gases: Group 8A; extremely Unreactive. • Why are group 8A elements unreactive? Answer: Their outer valence shell is filled, so they have no need to pair up with anyone else.

  11. Metalloids • Have properties of both metals and nonmetals. • Stair-step down from boron to astatine and germanium to polonium. • They separate the metals and nonmetals on the periodic table.

  12. Assignment • Label the following on your blank periodic table: • Groups & periods • Representative elements • Transition elements • Metals: alkali metals, alkaline earth metals, transition metals, and inner transition metals • Nonmetals • Halogens • Noble gases • metalloids

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