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Objectives
1. Describe characteristics of metals, nonmetals, and metalloids
2. Define period, periodic law, family, malleable, ductile
3. Describe how elements are arranged on the periodic table
Henry Mosley (1914)
Determined that each atom has a unique number of positive charges.
Discovered isotopes
Rearranged Mendeleyev’s table by their atomic number
Periodic Law
Because properties of elements repeated in an orderly way, it was called periodic.
Properties of elements are a function of their atomic numbers.
Electrons in the outer most energy level of an atom are called ________ electrons.
A. valence
B. oxidation
C. superior
D. bonding
Starting at the left of each period, the pattern of valence electrons is
A. 1 2 3 4 5 6 7 8
B. 0 1 2 3 4 5 6 7
C. 0 1 2 3 4 3 2 1
D. 4 3 2 1 0 1 2 3 4
The period 4 atoms each have 4 electron containing shells
K (Potassium)
AtomFe (Iron) Atom
Kr (Krypton)
Atom
4th Shell
Metals
shiny (they have luster) solids at room temperature good conductors malleable - capable of being
hammered out into thin sheets ductile - drawn out into wire or threads
Non-metals
Can be found as solids, liquids, or gases at room temperature
Typically dull and brittle Poor conductors All non-metals except hydrogen are
found on the right side of the zigzag line
Many valance electrons
Metalloids
Border both sides of the zigzag line each has some of the properties of a
metal and non metal can become good conductors under
certain conditions such as high temperatures
Also called semiconductors
The British scientist who rearranged the periodic table according to the atomic numbers of elements
A. JJ Thomson
B. Henry Moseley
C. Ernest Rutherford