early chemists used the properties of elements to sort them into groups, or triads. 1700: 13...
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Early chemists used the properties of elements to sort them into groups, or triads.
1700: 13 elements
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…
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…
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.
Mendeleev’s table predicted the properties of undiscovered elements.
Properties of GalliumMendeleev’spredictions
ActualProperties
Atomic mass 68 69.7
Density 6.0 g/cm3 5.9 g/cm3
Appearance soft gray metal soft gray metal
Melting point Low melting point 29.8°C
Elements later discovered:Gallium, Germanium, and Scandium
Gallium
Properties of GalliumMendeleev’spredictions
ActualProperties
Atomic mass 68 69.7
Density 6.0 g/cm3 5.9 g/cm3
Appearance soft gray metal soft gray metal
Melting point Low melting point 29.8°C
Elements later discovered:Gallium, Germanium, and Scandium
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
Period: a row across the table.
each period is an energy level
Group : a column down the table.
same group, similar prop’s
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.
Metallic less Metallic
3 classes of elements are:
Metals NonmetalsMetalloids(most elements)
Metals Nonmetals Metalloids
luster (shiny)malleable (sheets)
ductile (wires)good conductors
(heat/electricity)
most gasesbrittle solids
poor conductors
dull/shinybrittle
semi-conductors
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!
2. The modern periodic table is arranged by increasing..
A. mass number.
B. density.
C. atomic number.
D. intelligence.
Quick Quiz.
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.
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.
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.
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
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