Chapter 6 development of the periodic Table

This chapter explores how scientists discovered patterns among the elements and organized them into the modern periodic table we use today. Students will learn about the historical progression of ideas—from early attempts to classify elements based on their properties, to Mendeleev’s groundbreaking periodic law, and finally to the modern organization based on atomic number. The chapter highlights how the periodic table reflects recurring trends in atomic structure and chemical behavior, serving as a powerful tool for predicting the properties of elements. Key topics include early classification systems, Mendeleev’s periodic arrangement, Moseley’s atomic number concept, and the structure and meaning of modern groups and periods.

1. The Periodic Table
Section 1: Organizing the
Elements

2. Early chemists used the properties of
elements to sort them into groups, or triads.
1700:
13
elements

3. Newlands and Meyer arrange
elements by atomic mass and
notice similar properties.
1864:
56
elements
1869:
63
elements
Mendeleev arranged the elements
by increasing atomic mass and
by similar properties.

4. Mendeleev’s table predicted the properties
of undiscovered elements.

5. Properties of Gallium
Mendeleev’s
predictions
Actual
Properties
Atomic mass 68 69.7
Density 6.0 g/cm
3
5.9 g/cm
3
Appearance soft gray metalsoft gray metal
Melting pointLow melting point 29.8°C
Elements later discovered:
Gallium, Germanium, and Scandium

6. Gallium
Properties of Gallium
Mendeleev’s
predictions
Actual
Properties
Atomic mass 68 69.7
Density 6.0 g/cm
3
5.9 g/cm
3
Appearance soft gray metalsoft gray metal
Melting pointLow melting point 29.8°C
Elements later discovered:
Gallium, Germanium, and Scandium

7. Newlands and Meyer arrange
elements by atomic mass and
notice similar properties.
1864:
56
elements
1869:
63
elements
Dmitri Mendeleev got an idea from his
favorite card game…
Mendeleev arranged the elements
by increasing atomic mass and
by similar properties.
Moseley arranges elements by the
newly discovered “atomic number.”
1913:
atomic
numbers

8. Period: a row across the table.
each period is an energy level

9. Group : a column down the table.
same group, similar prop’s

10. The modern periodic table arranges elements
by increasing atomic number.
Periodic Law:
periodic repetition of properties
•properties change across a period.
•properties repeat from
period to period.

11. Metallic less Metallic
3 classes of elements are:
Metals NonmetalsMetalloids
(most elements)

12. Metals Nonmetals Metalloids
luster (shiny)
malleable (sheets)
ductile (wires)
good conductors
(heat/electricity)
most gases
brittle solids
poor
conductors
dull/shiny
brittle
semi-
conductors

13. 1. Mendeleev arranged the elements in his
periodic table in order of increasing
_________ and by _________ properties.
A.atomic number , similar
B.number of protons , repeating
C.number of electrons , similar
D.atomic mass , repeating
Quick Quiz!

14. 2. The modern periodic table is arranged
by increasing..
A.mass number.
B.density.
C.atomic number.
D.intelligence.
Quick Quiz.

15. 3. Elements in the same group have…
A.very little in common.
B.the same atomic number.
C.different chemical properties.
D.similar chemical properties.
Quick Quiz.

16. 4. Which one of the following is NOT a
general property of metals?
A.ductility
B.malleability
C.high luster
D.poor conductor of heat and electricity
Quick Quiz.

17. 5. Which list of elements contains only
nonmetals?
A. Sn , P , Cl
B. S , Na , O
C. Ge , Br , Ne
D. O , I , H
Quick Quiz.

18. 6.Identify each as metal, nonmetal, or metalloid:
A.Copper:
B.Boron:
C.Sulfur:
D.Sodium:
E.Tin:
F.Hydrogen:
Metal
Quick Quiz.
Metalloid
Nonmetal
Metal
Metal
Nonmetal

19. 7.Identify the following sample of an unknown
substance as a metal, nonmetal, or
metalloid:
solid at room temp.
Quick Quiz.
will break rather than bend
conducts electricity only at high temp’s
Metalloid