Periodic Table 18 Groups 7 Periods similar properties

Periodic Table 18 Groups 7 Periods similar properties same energy level 3 Classes of elements: Metals, metalloids, nonmetals. Most of the elements are metals!! (80%) Across a period, the properties of elements become less metallic and more nonmetallic.

6. 1 Metals, Nonmetals, and Metalloids

Groups Group 1: Alkali metals Group 2: Alkali earth metals Group 3 -12: Transition metals Group 17: Halogens Group 18: Noble Gases Two rows on the bottom: Rare-earth elements

Important Questions Q. How did chemists organize the elements? A. Properties!! Q. Who organized the 1 st periodic table? A. Mendeleev! Q. How did he organize it? A. Atomic mass! Q. How is the modern periodic table organized? A. Atomic number!

1869 -Dmitri Mendeleev -developed a table to show relationships between the elements -wrote properties of the elements on note cards and organized them -organized according to increasing atomic mass -arranged in groups based on repeating or “periodic” properties

6. 1 Mendeleev’s Periodic Table

6. 1 Moseley linked an element’s place on the periodic table to a physical characteristic, relationship between λ of x-ray and number of protons in the nucleus.

Periodic law: there is a periodic repetition of physical and chemical properties

Practice Problems 1. Which element should have properties similar to Cl? 2. Is sodium a metal, non-metal, or metalloid? 3. Name two elements that have properties similar to K? 4. What element is in group 13 period 3? 5. What is the name of group 18? 6. The first periodic table was organized according to?

Compare and Contrast Early and Modern periodic tables • How are they similar? • What does the position indicate about properties?

Trends Activity-pg 788 1. What do you notice about the boiling point and melting point as you move left to right? 2. What do you notice about the density as you move left to right? 3. Why is the range of densities much greater among the group 17 (pg 840) elements than the group 1 (pg 788) elements?