Introduction to the Periodic Table
Representative Elements
Transition Elements
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In 1830 there were 55 elements isolated and named
Dmitri Mendeleev’s (1869) developed a Table of
Elements by ordering them in increasing atomic mass
◦ Elements with similar properties fell into groups
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Mendeleev left 3 spaces for elements yet to be
discovered and spurred interest in finding those
elements (he also predicted their properties
◦ (15 years later all were identified)
 Henry
Moseley improved periodic table
by placing them in increasing atomic
number
 This made it possible to see exactly how
many elements yet to be discovered
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Ordered by increasing atomic number (protons)
Organized in rows call periods (1-7 rows)
◦ Properties change gradually from 1 row to next
Columns on the periodic table are called groups or
families (18 groups)
◦ Groups contain elements with similar physical and
chemical properties
◦ Representative elements (8 groups) are from
groups 1,2,13-18)
 Include elements that are metals, nonmetals,
metalloids
Transition elements: elements from group
3-12
◦ All are metals
 Inner transition elements are below main
table and include lanthanide and actinide
series
◦ (named by series that follows lanthanum and
actinium (most are radioactive)
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Are solid (with exception of Mercury Hg)
 Have high melting point
 Has metallic luster, good conductor of heat
and electricity
 Is malleable (can hammer it)
 Is ductile (can be stretched)
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Nonmetals are usually
◦ Gases or brittle solids at room temperature
◦ Poor conductors of heat and electricity
◦ 17 nonmetals, some are essential for life (O, C,S, N, P,
and I)
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Metalloids are usually:
◦ In between metals and nonmetals that share properties
of metals and nonmetals
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Shows name of element, symbol, atomic
number, atomic mass and the state of matter
(gas, liquid or solid)
One or two letter symbols where the first
letter is capitilized, second letter is small
letter ie Ca, Pb, Na, Si
 Some names come from first letter of element,
others greek or latin names, some for countries
discovered
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Groups 1 and 2
◦ Both groups are active metals (except H) because
they easily combine with others substances
◦ H shares properties with these groups
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Group 1
◦ Silvery solids with low density and low melting
points
◦ As move down the column they become more
reactive
◦ Include Li,Na,K,Rb,Cs, Fr
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Group 2
◦ Denser, harder and higher melting point than
group1 (alkali)
◦ Are reactive, but not as much as alkali metals
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Group 13 Boron Family
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all are metals except B which is a metalloid
◦ Cookware is made from B, Al for cans,Ga used in
computer chips
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Group 14 Carbon Family
◦ C is nonmetalic, Si and Ge are metalloids, Tn and
Pb are metals
 Semi conductors in computers are made from Si
because they conduct some electrical current but is
buffered to help maintain certain levels of
conductivity
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Group 15: Nitrogen groups
N,P,As,Sb,Bi (nonmetal,metalloid, and metals)
Nitrogen composed of 78% of atmosphere yet
it can’t be utilized by organisms until it is
change to nitrates
Nitrogen fixing bacteria on roots of
organisms can fix nitrogen into nitrates
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Group 16 Oxygen Family
O and S are essential for life
Te and Po are both metalloids
20% earths atmosphere is made of O
◦ Needed for respiration for energy production of animals
◦ O is needed for combustion, ozone layer protects us from
ultraviolet radiation
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S is solid, yellow nonmetal, used in sulfuric acid,
production of fertilizers, rubber etc
Se is important as trace minerals, conducts electricity
Group 17 Halogen family
 All are nonmetals except At radioactive
metalloid
 Halogen means salt-former like NaCl
 All halogens make salt
 As move down the group they become less
active
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Group18 The Noble Gases
 All are gases, do not react with other elements
 Uses include the Neon lights in advertisments
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◦ Electricity passes through tubes containing noble
gases that when mixed with noble gases produces
different colored lights
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Bottom of group is radioactive Ra
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Metals in the Middle: groups 3-12
Iron Triad (similar properties)
Iron Fe, cobalt Co, and nickel Ni
Fe used with other metals and C to form alloys like
steel
Uses of Transition Elements
◦ Higher melting points, used in filaments of lightbulbs:
tungsten W has highest melting point (3410℃)
◦ Mercury Hg, lowest melting point -39℃
◦ Platinium group Ru,Rh, Pa, Os, Ir, Pl similar properties
 Catalysts are substanes that can make something happen faster but
doesn’t change themselves (platinium group)
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Lanthanides series: rare earths because not
found commonly on earth
◦ Soft metals, hard to tell apart in same ores, Ce
makes up 50%of an alloy called misch used in flints
lighters
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Actinides series: all are radioactive Th, Pa and
U are only ones found in nature
◦ Rest are synthetic elements (man made)
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Dentistry and Dental Material
◦ Amalgam (mixture of silver, copper, tin, and
mercury) is the silver filling
◦ Nickel and titanium alloys are used in wires on
braces