Transcript Periodic_table

The Periodic Table Revisited
• The periodic table is based on chemical
properties.
• Chemical behavior is determined by
electron configuration,
• The position on the table corresponds
to the electron configuration
• Electron configurations
The periodic table
• Know where the metals are located
• Know where the non-metals are located
• Know where the transition metals and
semi-metals are located
• Periodic table blocks
Electron configurations
• The representative metals are in groups IA, IIA,
and IIIA.
– They have valence electrons in S1,S2, and S2P1
• The Nobel gases
– All have an S2P6 Configuration
• The non metals all have partially filled P
sublevel
• The transition metals have partially filled D
sublevels
• The inner transition metals have partially filled f
sublevels
• Electron configurations
Covalent atomic radius
One half the distance betweeen nuclei
of atoms in a diatomic molecule
Atomic size
High shielding = large atom
High nuclear pull= small atom
1. Shielding increases
because each row
represents one more
energy level
2. As shielding increases,
the electrons spread out,
and the atom increases in
size
3. As the atom is larger –
outer electrons can drift
away easier
4. Metals become more
reactive
5. Nonmetals become less
reactive
Group
Trends
1. As the nuclear
charge increases,
the atoms are
drawn in tighter
2. The atomic radius
decreases
3. Metals become
less reactive
4. Nonmetals become
more reactive
Period trends
Ionization energy: energy required to
remove an electron from a gaseous atom
• As we move down the group – shielding
increases and ionization energy
decreases
• Metals become more reactive, non
metals become less reactive
• As we move across a period, nuclear pull
becomes greater – and ionization energy
increases
• Metals become less reactive, non metals
become more reactive
Ionization energy
Low shielding = high ionization energy
High nuclear pull = high ionization energy
The Electron affinity indicates the
energy change when an electron is
added to a gaseous atom or ion.
• As we move down a group, shielding
increases, and electron affinity is lower
• As we move across a period, shielding
remains the same, but nuclear pull
increases – and this increases electron
affinity
• Non metals have a high electron affinity
Electron affinity and
Electronegativity
Low shielding = high electron affinity
High nuclear pull = high electron affinity
Trends in ion size
Cations are smaller
than the atoms that
they come from
Anions are larger
than the atoms
that they come
from
Periodic trends
• Worksheet with answers