Aim: How are Elements Organized in the Periodic Table? DO Now: 1. How would you organize these buttons? 2. How do you think elements are organized in the periodic table? 3. Write at least one trend you notice about the elements in the periodic table.

History of the Periodic Table The first periodic table was developed in Russia in 1869 by chemist Dmtri Mendeleev; he arranged the elements in order of increasing atomic mass. The modern periodic law states: elements are arranged in order of increasing atomic numbers. Chemists use the properties of elements to sort them into groups.

Periods and Groups Periods Groups or Families Vertical columns Horizontal rows The # of the period indicates the # of energy levels (shells) in the element The # of valence electrons (electrons in outer shell) increases from right to left Properties of elements change across a period Vertical columns Most elements within the same group have the same number of valence electrons (electrons in outermost shell); therefore, have similar chemical properties

Three Classes of Elements Metals Alkali Metals Alkaline Earth Metals Transition Metals Inner Transition Metals Metalloids Nonmetals Halogen Noble Gases

Metals vs Non Metals Properties Metals solids at room temperature are malleable are ductile have luster good conductors of heat and electricity Properties of Nonmetals many are gases at room temperature not malleable, tend to be brittle in the solid phase. surface is dull poor conductors of heat and electricity

Metallic Character The metallic character of an element can be defined as how readily an atom can lose an electron. Metallic characteristics decrease from left to right across a period, and  increase down a group.

Alkali Metals and Alkaline Earth Metal Alkaline Earth Metals Group 1 Most active metals in the periodic table All react vigorously with water to produce H2(g) They are shiny, have the consistency of clay, and are easily cut with a knife. Reactivity increases as you go down this period Group 2 Second most active metals

Transition Metals and Inner Transition Metals The elements in Groups 3 through 12 Typically hard solids with high melting points, with the exception of mercury Form colored compounds. Are good conductors of heat and electricity. Can be hammered or bent into shape easily.(malleable) Are less reactive than alkali metals such as sodium.

Metalloids They can be found adjacent to the stair-step line in the periodic table. Have properties similar to those of metals and nonmetals. Solids Can be shiny or dull Ductile Malleable Conduct heat and electricity better than nonmetals but not as well as metals

Metalloids Cont. boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te), and polonium (Po) are the elements found along the step like line between metals and non-metals of the periodic table.

Halogens Group 17 Halogens have 7 valence electrons, which explains why they are the most active non-metals Have low melting points and boiling points Chemical reactivity decreases as you go down the group

Noble Gases Group 18 Colorless gases Do not chemically react with other elements (inert or stable) Are isolated atoms

Activity Given the blank periodic table fill in each category with a different color. Alkali Earth Metals 6. Nonmetals 2. Alkaline Earth Metals 7. Nobles Gases 3. Transition Metals 8. Metalloids 4. Inner transition Metals 9. Other Metals 5. Metalloids 10. Halogens