The Periodic Table and Periodic Law 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.

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

The Modern Periodic Table What are columns called? Answer: Groups What are horizontal rows called? Answer: Periods Label groups and rows on your blank periodic table as instructed, or as they are labeled on pp of your textbook, if you are absent.

The Modern Periodic Table (continued) Representative elements: elements in the A groups (1A-8A) –AKA, “the main group” –Possess a wide range of physical and chemical properties Transition elements: elements in the B groups (1B-8B) A more recent numbering system (1-18) is shown in your book., but what is an advantage to using the older system?

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.

Metals (continued) Groups 1A and 2A, EXCEPT HYROGEN, are metals. If H is so different, why is it in groups 1A? What does it have in common with the other elements in that group? (Hint: last test) The other elements in group 1A are called alkali metals. Group 2A elements are alkaline earth metals.

Metals (continued) 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.

Metals (continued) 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

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

Nonmetals (continued) 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.

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.

Assignments 1.Color-code the metals, nonmetals, and metalloids on your blank periodic table. 2.Complete Study Guide for Content Mastery, p.32 (18-29)