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PeriodicProperties
of the Elements
Chapter 5Periodic Table /
Elements
John D. Bookstaver
St. Charles Community College
St. Peters, MO
2006, Prentice Hall, Inc.
Chemistry, The Central Science, 10th editionTheodore L. Brown; H. Eugene LeMay, Jr.;
and Bruce E. Bursten
PeriodicProperties
of the Elements
Video
PeriodicProperties
of the Elements
Symbols of Elements
Elements are symbolized by one or two letters.
PeriodicProperties
of the Elements
Atomic Number
All atoms of the same element have the same number of protons:
The atomic number (Z)
PeriodicProperties
of the Elements
Atomic Mass
The mass of an atom in atomic mass units (amu) is the total number of protons and neutrons in the atom.
PeriodicProperties
of the Elements
Periodic Table:
• A catalog of elements.
• Elements are arranged in order of atomic number.
PeriodicProperties
of the Elements
PeriodicProperties
of the Elements
Periodicity
When one looks at the chemical properties of elements, one notices a repeating pattern of reactivities.
PeriodicProperties
of the Elements
Periodic Table• The rows on the
periodic chart are periods.
• Columns are groups.• Elements in the same
group have similar chemical properties.
PeriodicProperties
of the Elements
Groups
These five groups are known by their names.
PeriodicProperties
of the Elements
Periodic Table
Nonmetals are on the right side of the periodic table (with the exception of H).
PeriodicProperties
of the Elements
Periodic Table
Metalloids border the stair-step line (with the exception of Al and Po).
PeriodicProperties
of the Elements
Periodic Table
Metals are on the left side of the chart.
PeriodicProperties
of the Elements
Periodic Table
• We fill orbitals in increasing order of energy.
• Different blocks on the periodic table, then correspond to different types of orbitals.
PeriodicProperties
of the Elements
Development of Periodic Table
• Elements in the same group generally have similar chemical properties.
• Properties are not identical, however.
PeriodicProperties
of the Elements
Development of Periodic Table
Dmitri Mendeleev and Lothar Meyer independently came to the same conclusion about how elements should be grouped.
PeriodicProperties
of the Elements
Development of Periodic Table
Mendeleev, for instance, predicted the discovery of germanium (which he called eka-silicon) as an element with an atomic weight between that of zinc and arsenic, but with chemical properties similar to those of silicon.
PeriodicProperties
of the Elements
Ionization Energy
• Amount of energy required to remove an electron from the ground state of a gaseous atom or ion.
PeriodicProperties
of the Elements
Trends in First Ionization Energies
• As one goes down a column, less energy is required to remove the first electron.
PeriodicProperties
of the Elements
Trends in First Ionization Energies
• Generally, as one goes across a row, it gets harder to remove an electron.
PeriodicProperties
of the Elements
Properties of Metal, Nonmetals,and Metalloids
PeriodicProperties
of the Elements
Metals versus Nonmetals
Differences between metals and nonmetals tend to revolve around these properties.
PeriodicProperties
of the Elements
Metals versus Nonmetals
• Metals tend to form cations.• Nonmetals tend to form anions.
PeriodicProperties
of the Elements
Metals
Tend to be lustrous, malleable, ductile, and good conductors of heat and electricity.
PeriodicProperties
of the Elements
Metals
• Compounds formed between metals and nonmetals tend to be ionic.
PeriodicProperties
of the Elements
Nonmetals
• Dull, brittle substances that are poor conductors of heat and electricity.
PeriodicProperties
of the Elements
Nonmetals
• Substances containing only nonmetals are molecular compounds.
• Most nonmetal oxides are acidic.
PeriodicProperties
of the Elements
Metalloids
• Have some characteristics of metals, some of nonmetals.
• For instance, silicon looks shiny, but is brittle and fairly poor conductor.
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