Download 6.6 – Periodic Table

6.6 – Periodic Table
History of the Periodic Table
Dmitri Mendeleev (1869) – Arranged the known elements in order of increasing atomic mass.
Modern Periodic Law – Elements today are arranged according to their atomic numbers (or number of
protons).
Organization of the Periodic Table
Group or Family – Vertical column on the periodic table. These elements in groups or families usually share
similar chemical properties.
Period – Horizontal row on the periodic table. These elements have the same number of occupied energy
levels.
Valence Electrons – Electrons found in the outermost shell of an atom. These electrons determine the atom’s
chemical properties.
6.6 – Periodic Table
Physical Properties of the Periodic Table
Metals – Excellent conductors of heat and electricity. Often ductile (able to be squeezed out into a wire) and
malleable (able to be hammered into sheets). Tend to lose electrons (or become positively charged). Can be
mixed with other metals to form a mixture called an alloy. Usually found as solids at room temperature. Found
on the left side and bottom of the periodic table.
Nonmetals – Poor conductors of heat and electricity. Often gases at room temperature. Solids are
brittle. Tends to gain electrons (or become negatively charged ions) or share electrons. Found on the right side
of the periodic table. Tend to be semiconductors of electricity.
Metalloids – Found on the staircase of the periodic table. Has some characteristics of metals and some of
nonmetals. All metalloids are solids at room temperature.
6.6 – Periodic Table
Families of the Periodic Table
Alkali Metals – Group 1. One valence electron. Electron configuration ends in s1. Tends to lose 1 electron to
become +1 charge. Very reactive metals.
Alkaline Earth Metals – Group 2. Two valence electrons. Electron configuration ends in s2. Tends to lose 2
electrons to become +2 charge.
Halogens – Group 17. Seven valence electrons. Electron configuration ends in s2 p5. Tends to gain 1 electron
to become -1 charge. Very reactive nonmetals.
Noble Gases - Group 18. Eight valence electrons (Helium has two). These are very unreactive gases because
they have a full set of electrons in their outer energy level.
Transition Metals – d-block metals.
Inner Transition Metals – f-block metals. Include the Lanthanide Series and Actinide Series.
6.6 – Periodic Table
Periodic Trends
Nuclear Charge - Electrons are attracted to the protons in the nucleus. The closer the electron is to the nucleus,
the more strongly an electron is attracted. The more protons in the nucleus, the more strongly an electron is
attracted.
Atomic Radius – The size of the atom.
Atomic Radius Decreases:

To the Right due to the Nuclear Charge increasing. A greater number of protons create more attraction
of the valence electrons to the nucleus.