Periodic Law and Periodic Trends

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Periodic Law and Periodic Trends
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Periodic Law

• "when the elements are arranged in order of
  increasing atomic mass, certain sets of
  properties recur periodically.
• Dmitri Mendeleev, 1869
• "Similar properties recur periodically when
  elements are arranged according to increasing
  atomic number." -Henry Moseley, 1913

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Periodicity

• trends or recurring variations in element
  properties with increasing atomic number (
  protons).
• Periodicity is caused by regular and predictable
  variations in element atomic structure.

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Periodic Trends

• Patterns present in the periodic table when
  elements are arranged by atomic number
• Allow chemists to predict the physical and
  chemical properties of an element based upon its
  position on the periodic table.

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Periodic Trends

• Electronegativity
• Ionization Energy
• Electron Affinity
• Atomic Radius
• Melting Point
• Metallic Character
• Understand each property and describe the trends
  found on the periodic table

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Electronegativity

• The tendency of an atom of a element to attract
  electrons to itself.
• Not a property of an atom by itself but of an
  atom bonded in a molecule.
• Chemical property affected by nuclear charge
  and the number of electron shells

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Ionization Energy

• The minimum amount of energy required to remove a
  single electron from an atom of an element in the
  gaseous phase.
• Chemical property expressed in molar terms
  kJ/mol or kcal/mol
• Chemical property affected by nuclear charge
  and the number of electron shells

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Electron Affinity

• The change in energy (in kJ/mole) of a neutral
  atom (in the gaseous phase) when an electron is
  added to the atom to form a negative ion.
• In other words, the neutral atom's likelihood of
  gaining an electron.
• Metals Metals like to lose valence electrons to
  form cations to have a fully stable octet.
• Nonmetals Nonmetals like to gain electrons to
  form anions to have a fully stable octet.

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Atomic Radius

• A measure of the size of an elements atoms,
  usually the average distance from the nucleus to
  the boundary of the surrounding cloud of
  electrons.
• Due to nuclear charge and electron shells

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Melting Point

• The temperature at which a solid turns into a
  liquid.
• Physical property of an element.
• The stronger the bonds between atoms of an
  element, the higher the melting point

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Melting Point Trends

• Metals generally possess a high melting point.
• Most non-metals possess low melting points.
• The non-metal carbon possesses the highest
  boiling point of all the elements.

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Metallic Character

• How easily an atom can lose an electron
• Non-metallic character relates to how easily an
  atom of an element can gain an electron

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• Metallic Character

• Non-Metallic Character