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.

Periodic Table Investigation Look at the periodic. How are the elements organized from left to right? What are the rows labeled as? What are the columns labeled as? What do you notice is the same for all elements within the same column?

History of the Periodic Table The first periodic table was developed by chemist Dmitri Mendeleev; arranged elements in order of increasing atomic mass. (look at Te and I; not in order of increasing mass) The modern periodic law states: elements arranged in order of increasing atomic numbers. Elements are sorted into groups based on similar properties.

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 outer electrons increases from left to right Properties of elements change across a period Vertical columns Most elements within the same group have the same number of electrons in the last shell; therefore, have similar chemical properties

Why do elements within the same group have similar chemical properties Elements within the same group combine with other elements in similar ways Elements within the same group have the same number of valence electrons Valence electrons are the electrons located in the last shell of the atom

Three Classes of Elements 1.Metals Alkali Metals Alkaline Earth Metals Transition Metals Inner Transition Metals 2.Metalloids 3.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

Metalloids an element (e.g., germanium or silicon) whose properties are intermediate between those of metals and solid nonmetals

Question Explain in terms of valence electrons why beryllium and magnesium have similar chemical properties. 2. Which one of the following is not a property of metals? a. ductility b. malleability c. good electrical conductivity d. having a dull appearance e. good heat conductivity