1. Development of the Periodic Table

2. Early chemists used the properties of elements to sort them into groups, or triads.
1700:
13 elements
About 13 elements in 1700, then Scientific process discovered many more

3. 1864:
56 elements
Newlands and Meyer arrange elements by atomic mass and notice similar properties.
1869:
63 elements
Dmitri Mendeleev got an idea from his favorite card game…

4. 1864:
56 elements
Newlands and Meyer arrange elements by atomic mass and notice similar properties.
1869:
63 elements
Dmitri Mendeleev got an idea from his favorite card game…

5. 1864:
56 elements
Newlands and Meyer arrange elements by atomic mass and notice similar properties.
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.

6. Mendeleev’s table predicted the existence and properties of undiscovered elements.

7. The four predicted elements lighter than the rare-earth elements, eka-boron, eka- aluminium, eka-manganese (Em), and eka-silicon,proved to be good predictors of the properties of scandium, gallium, technetium and germanium respectively.

8. Elements later discovered: Gallium, Germanium, and Scandium
Properties of Gallium
Mendeleev’s
predictions
Actual
Properties
Atomic mass 68
69.7
Density
6.0 g/cm3
5.9 g/cm3
Appearance
soft gray metal
Melting point
Low melting point
29.8°C
Later scandium too

9. Elements later discovered: Gallium, Germanium, and Scandium
Properties of Gallium
Mendeleev’s
predictions
Actual
Properties
Atomic mass 68
69.7
Density
6.0 g/cm3
5.9 g/cm3
Appearance
soft gray metal
Melting point
Low melting point
29.8°C
Later scandium too

10. 1864:
56 elements
Newlands and Meyer arrange elements by atomic mass and notice similar properties.
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

11. Period: a row across the table.

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

13. 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.

14. 3 classes of elements are:
Metals
Metalloids
Nonmetals
(most elements)
Metallic less Metallic

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

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

17. Quick Quiz.
2. The modern periodic table is arranged by increasing..
mass number.
density.
atomic number.
intelligence.

18. Quick Quiz.
3. Elements in the same group have…
very little in common.
the same atomic number.
different chemical properties.
similar chemical properties.

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

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

21. Quick Quiz.
6. Identify each as metal, nonmetal, or metalloid:
Copper:
Boron:
Sulfur:
Sodium:
Tin:
Hydrogen:
Metal
Metalloid
Nonmetal
Metal
Metal
Nonmetal

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