2. Compare early attempts at organizing the
elements to the modern periodic table;
Explain how elements are arranged in the
modern periodic table; and
Identify three broad classes of elements and
their properties.
3. First attempts to organize elements was
based on their properties
J.W. Dobereiner organized them into triads
◦ Groups of three elements with similar properties
◦ Middle element had properties that were between
the other two
Example: Cl, Br, I
4. Dimitri Mendeleev organized elements by
increasing atomic mass
◦ Saw periodic, repeating pattern of properties
◦ Also had holes for undiscovered elements
◦ When they were discovered, matched his
predictions
6. Periodic law: when elements arranged by
increasing atomic number, there is a periodic
repetition of their physical and chemical
properties
◦ Holds for all elements, unlike Dobereiner
◦ Differs from Mendeleev, who used atomic mass
8. ~80 % of elements
Good conductors of heat & electric currents
High luster (shiny)
◦ Ability to reflect light
Solid at RT
◦ Except Hg (mercury)
Ductile—can form wires
Malleable—can make thin sheets without
breaking
9. Found in the upper right corner.
Most are gases at RT
◦ N, O
A few are solids
◦ Sulfur & Phosphorus
1 liquid
◦ Br
11. Properties of both metals & nonmetals
Depends on the conditions
Example Silicon
◦ Poor conductor
◦ Add small amount of boron—now a good conductor
12.
13. Compare early attempts at organizing the
elements to the modern periodic table?
Explain how elements are arranged in the
modern periodic table?
Identify three broad classes of elements and
their properties?
