Atomic Trends Notes

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Atomic Trends Notes
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Atomic Trends

• The number of protons and electrons affects the
  properties of an atom.
• The periodic table is organized according to
  groups (up and down) and periods (right to left).

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Atomic Trends

• There are a number of atomic characteristics that
  either increase or decrease along the periodic
  table

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Atomic Trends

• 1. Atomic Radius--the size of the atom. If you
  compare two atoms that are directly above and
  below each other on the table, the one underneath
  will be larger because it has an extra energy
  level full of electrons.

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Atomic Radius (cont.)

• However, if you compare two atoms that are
  side-by-side on the table, the one on the left
  will be larger because when you add more
  electrons and protons, the electric force that
  pulls them together will increase, making the
  radius smaller.

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Atomic Trends

• 2. Ionization Energy--the amount of energy that
  is required to remove an electron.
• If an atom will easily lose an electron (like the
  Alkali Metals), the ionization energy will be
  low.
• If it will not lose electrons easily (noble
  gases, Halogens), the ionization energy will be
  high.

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Ionization Energy (cont.)

• Ionization energy increases going left to right
  on the table, and decreases going down. Larger
  atoms lose electrons easier because the electric
  force is less because the distance from the
  nucleus is greater.

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Atomic Trends

• 3. Electron Affinity--the ability of an atom to
  gain an electron. This is closely related to
  ionization energy, and increases going left to
  right, and decreases going down.

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Atomic Trends

• 4. Electronegativity--Ability of an atom to
  attract electrons when in a molecule.

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Electronegativity (cont.)

• This increases going left to right, and decreases
  going down (with the exception of noble gases,
  which dont make molecules with other atoms).

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Atomic Trends