Transcript Chemical Bonding

Chemical Bonding
What kinds of bonding are there?
Chemical Bonding
• Electrostatic Force = force existing as a
result of the attraction or repulsion
between 2 charged particles
• Opposites attract; Like repel
• Greater distance  smaller attractive/
repulsive force (and vice-versa)
Atomic Radius Trend
• Going from left to right across a given period, the
atomic number (no. of p) increases  positive
charge on the nucleus (nuclear charge) increases.
• This means that there is a greater force of
attraction for the electrons in the shell and the
distance between the electrons and the nucleus
decreases.
Atomic Radius Trend
• Going across the row, atomic radius
decreases.
• Going down the group, atomic radius
increases because the more electrons
around the nucleus, the greater the volume
needed to contain them (since electrons
repel each other and can’t easily be
“compacted”.
Revisit Shells
• Open shell = containing less than its
maximum no. of e
• Closed shell = containing its maximum no.
of e
• Valence electrons = electrons in OPEN
shells
Schematic for No. of Valence
Electrons
Note
• For purposes of this section, only
valence electrons are considered for
bonding and the transition metals
(lanthanides and actinides) are
ignored.
Lewis Structure
• Show how valence electrons are
distributed for Ga, As and Kr
Lewis Structure
What is Valence?
• Valence is NOT valence electrons.
• Valence of an atom = the number of
unpaired electrons. It is sometimes
also called the combining capacity.
What is Ionization Energy?
• In order to form a positive ion, an
electron must be removed from a
neutral atom.
• Ionization energy = the energy
required to REMOVE electron from a
neutral atom.
Ionization Energy Trend
• Ionization energy INCREASES across a
period (higher positive nuclear charge to
attract the electrons, so hard to remove
them)
• DECREASES down a group since each shell
is further from the nucleus (less nuclear
charge)