1. 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.

2. 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.

3. 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 left to right
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

4. Three Classes of Elements
1.Metals
Alkali Metals
Alkaline Earth Metals
Transition Metals
Inner Transition Metals
2.Metalloids
3.Nonmetals
Halogen
Noble Gases

6. 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

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