Transcript Atomic Trends Notes

Atomic Trends Notes
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).
Atomic Trends
• There are a number of atomic characteristics
that either increase or decrease along the
periodic table:
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.
Atomic Radius (cont.)
• However, if you compare
two atoms that are sideby-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.
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.
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.
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.
Atomic Trends
• 4. Electronegativity-Ability of an atom to
attract electrons when
in a molecule.
Electronegativity (cont.)
• This increases going
left to right, and
decreases going
down (with the
exception of noble
gases, which don’t
make molecules with
other atoms).
Atomic Trends