Elements and the
Periodic Table
A Brief History….
Ancient Names for the
elements
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Plumbum
Natrium
Aurum
Argentum
Hydrargyrum
Kalium
Ferrum
John Dalton - Atomic Theory
Proposed in 1803:
(1) all matter was composed
of small indivisible
particles termed atoms,
(2) atoms of a given element
possess unique
characteristics and weight
(3) three types of atoms
exist: simple (elements),
compound (simple
molecules), and complex
(complex molecules).
Symbols for the elements used by
Dalton
Dalton’s Symbols
Jons Jacob Berzelius (1779-1848)
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Proposed using the
first or a second
letter for the
element symbol.
Modern Element Symbols
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Each element has its own symbol.
In writing a symbol, we use 1 or 2 letters.
The first letter is always capitalized, the
second is not.
Some elements kept symbols for Latin or
Greek words.
Elements are grouped in the periodic table.
The Periodic Table
The Periodic Table
The periodic table is a system which
helps to classify the elements.
 In 1735, there were only 13 known
elements; in 1850, there were 47;
today there are over 100, including
several man-made elements.
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The Periodic Table (continued)
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The periodic table
we use today was
devised by a
Russian scientist
named Dmitri
Mendeleev in 1869.
Mendeleev’s Periodic Table
Mendeleev’s Periodic Table
Mendeleev’s Periodic Table
Other Attempts…..
Other Attempts…..
Periodic Table Information
A periodic table can tell us many things:
 Elements are arranged in order of
atomic numbers (number of protons in
the nucleus)
 Atomic weight or mass of an element
(number of protons and neutrons)
 Metals and non-metals are separated
in the upper right corner by a zigzag
line.
Metals and non-metals
Metals
Properties of metals
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All solids at room temperature, except
mercury (liquid)
Shiny
Malleable (bendable)
Good conductors of heat and/or electricity
Ductile (can be drawn into thin long wires)
Most react with acids
Located left of the staircase line in the
periodic table.
Non-metals
Properties of non-metals
Most are gases, some are solids,
bromine is the only liquid,
 Dull
 Brittle
 Poor or nonconductors
 Do not react with acids
 Located right of the staircase line in
the periodic table.
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Metalloids (semi-metals)
Elements that have some properties
of metals and some of nonmetals.
 Include all elements on either side of
the staircase line except AL and At.
 Also includes one form of C, called
graphite, which is dull and brittle
(nonmetal) but is a good conductor of
electricity (metal).
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Periodic Table Information
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Horizontal rows are called periods.
Vertical columns are called groups or
families (all elements in the same group
have similar characteristics).
The group number is the number of electrons
in the outside level or orbit of an atom. These
are called valence electrons.
The groups on the periodic table have
different names:
Group A – Representative elements (1,2,1318)
Group B – Transition elements (3-12)
Chemical Families (groups)
Group 1 (IA) – alkali metals
 Group 2 (IIA) – alkaline earth metals
 Group 17 (VIIA) – halogens
 Group 18 (VIIIA) – noble gases
 Rows on the bottom:
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Lanthanide series
 Actinide series
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Chemical Families – Alkali metals
group 1, IA
- Eg. Sodium, lithium
- Show metallic
properties
- Highly reactive,
especially with water;
reactivity increases
down the group
- Cs and Fr are the
most reactive metals.
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Alkaline earth metals
Group 2, IIA
- Eg. Calcium, magnesium
- show metallic properties
- less reactive than alkali metals;
reactivity increases down the group
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Halogens
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Group 17, VIIA
Eg. Chlorine, fluorine
show nonmetallic properties
reactivity decreases going down the
group; F is the most reactive nonmetal
react with metals to produce salts
(ionic compounds)
react with hydrogen to form
compounds that dissolve in water to
form acids.
Noble Gases
Group 18, VIIIA
- Helium, neon, argon
- show nonmetallic properties
- extremely low chemical reactivity
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