What Are the Trends in the Periodic Table

Chapter 4-3

What are the trends in the periodic table?

electron shielding

inner electrons shield the outermost electrons from the full charge of the nucleus

as a result outermost electrons are not held as close to the

nucleus

Atomic radius

Measure of the size of the atom

Increases as you move down a group; caused by the

addition of another main energy level from one period to the next

as n increases, the number of inner electrons increases,

electron shielding increases

for Li

nuclear charge = +3

effective nuclear charge (actual charge experienceds by the electrons) < +3

atomic radius decreases as you move across a period

from left to right within a period, each atom has one more

proton and one more electron than the element before it

additional electrons are going in the same main energy level

electron shielding remains constant

nuclear charge increases but the outer electrons are still in the 2nd energy level

outer electrons are attracted more strongly toward the nucleus resulting in smaller size

perioic trends in ionization energies are opposite those for

atomic size

decreasing atomic size

outermost electrons held more tightly to nucleus

increasing energy to remove outermost electrons

increasing ionization energy

increasing atomic size

outermost electrons held less tightly to nucleus

decreasing energy to remove outermost electrons

decreasing ionization energy

Ability of an atom to attract and hold an added electron

Energy emitted upon the addition of an electron to an atom or group of atoms in the gas phase

decreasing atomic size

increasing nuclear charge

increasing electron affinity

increasing electron shielding

increasing atomic size

decreasing electron affinity

ionization energy and electron affinity are properties of isolated atoms

electronegativity

measure of the ability of an atom in a bond to attract

electrons to itself

same periodic trend as electron affinity