periodic trends learning target: criteria for success:
DESCRIPTION
Periodic Trends A. Attraction between the nucleus and electrons 1. Coulomb’s law- the force of attraction between two oppositely charged particles is directly proportional to the magnitude of the charges and inversely proportional to the distance between those charges.TRANSCRIPT
Periodic TrendsLearning Target:• I can use the Periodic Table to identify and explain periodic trends,
including atomic and ionic radii, electronegativity, and ionization energy.
Criteria For Success:• I can explain effective nuclear charge and electron shielding.• I can explain how increasing effective nuclear charge across a period
influences the atomic radius, electronegativity and ionization energy.• I can explain how increased electron shielding down a group
influences atomic radius, electronegativity and ionization energy.• I can explain the trend of ionic radius and how the magnitude and
the sign of the ionic charge influences ionic radius
Periodic TrendsA. Attraction between the nucleus and electrons• 1. Coulomb’s law- the force of
attraction between two oppositely charged particles is directly proportional to the magnitude of the charges and inversely proportional to the distance between those charges.
Periodic TrendsCoulomb’s Law
Periodic Trends2. Effective nuclear charge (Zeff)- the net nuclear pull experienced by the valence electrons in an atom.
a. Zeff = # protons - # core (non-valence) electrons
Periodic Trends
http://inntrending.com/effective-nuclear-charge-trends/
Periodic Trends
http://inntrending.com/effective-nuclear-charge-trends/
Periodic Trends3. Electron shielding- the inner electrons shield the outer electrons from some of the nucleus’ attractive force.• a. Going down a group adds another
principle energy level adds more shielding.
Periodic Trends
Periodic Trendsb. Adding another energy level also increases the distance between the outer electrons and the nucleus which decreases the force- Coulomb’s Law!
Periodic Trends
Periodic Trends• B. Periodic trends are patterns
in the periodic table relating to the size and other properties of elements.
Periodic Trends1.ATOMIC RADIUS is the
distance between the nucleus and the outer edge of the electron cloud.
Periodic Trends
Periodic Trends
Periodic Trends
2.IONIZATION ENERGY is the energy required to remove an electron from the atom.
Periodic Trendsa) Each additional electron requires
MORE energy to remove than the previous one, so the second ionization energy will be greater than the first ionization energy, and so on.
Periodic Trends
Periodic Trends
Periodic Trendsb. EXCEPTIONS!!!
O vs. N- It’s easier to remove an electron from O because of the repulsion of the paired electrons.
Periodic Trendsb. EXCEPTIONS!!!
Be vs. B- It’s easier to remove an electron from B because it’s a p electron vs. an s electron and electrons in p orbitals are held less tightly.
Periodic Trends3. ELECTRONEGATIVITY is the ability of
an atom in a molecule [meaning it’s participating in a bond] to attract shared electrons to itself.a. Think of the atoms as playing “tug
of war” with their outer shell electrons.
Periodic Trends
Periodic Trends
Periodic Trends4.IONIC RADIUS is the distance
from the nucleus to the outer edge of the electron cloud in a charged ion.
Periodic Trendsa. Cation- the atom LOST electron(s),
has a positive chargeb. Anion- the atom GAINED
electron(s), has a negative chargec. All atoms want a full valence shell,
and will gain/lose electrons to get there.
Periodic TrendsCharges of Ions
Periodic Trends
Periodic TrendsC. Periodic trends can be justified by using one of the following generalizations:
1. Use Z eff to explain trends across a period.2. Use electron shielding (increased energy
levels, increased distance) to explain trends down a group.