CHAPTER 4 ATOMS AND
ELEMENTS
Section 6 Looking for Patterns: The Periodic
Table
DMITRI MENDELEEV, 1869
Russian Chemist – first to systematically
organize the elements.
 Noticed that groups of elements had similar
properties.
 By listing the elements according to increasing
relative mass, those with similar properties
recurred in a regular pattern.
 Periodic Law: When the elements are
arranged in order of increasing relative
mass, certain sets of properties recur
periodically.

THE PERIODIC TABLE OF ELEMENTS

Metals – left side of table
 Luster – shiny (reflect light)
 Malleable – can be hammered into thin
sheets
 Ductile – can be drawn out into a wire
 react with nonmetals – ex. Al2O3
 group IA are most reactive (not found free in
nature);
 those in the middle can be found in nature as
free elements (Cu, Ag, Au …);
 good conductors of heat and electricity
 Most are solids at room temperature
PERIODIC TABLE
 Non-Metals






– right side of table
Brittle (not malleable or ductile)
Poor conductors
Combine with metals (CuO) or one
another (CO2)
do not conduct electricity
Fluorine is the most reactive non-metal
Can be found in nature as free elements
(ex. Carbon, Oxygen, Sulfur)
PERIODIC TABLE
 Metalloids
– along the stair stepping line
 Semiconductors – used in electronics
industry (transistors, computer chips;
Compounds with Silicon, SiO2 are very
common and widely used.
PERIODIC TABLE CONTINUED

Groups or Families – up and down

Ex. IA – Alkali Metals, IIA – Alkaline metals, VIIA
Halogens
Period or Series – horizontal rows
 Diatomic Elements – pairs of atoms combined
chemically at typical room conditions.

H, O, F, Br, I, N, Cl
 7 of them, form the number 7 on the periodic table
 Most are located in the halogen family

PERIODIC TABLE - PHYSICAL STATES
 Most
elements in the periodic table are
solids at room conditions
 Only 2 elements are liquids – bromine (a
very reactive nonmetal) & mercury
(metal)
 Noble
Gases
All gases at room temperature
 Un-reactive elements

HOMEWORK
Read Chapter 4 sections 6 on pages 102-106
 Answer questions on page 119 #52-70 even
