Periodicity Flashcards
(23 cards)
What is periodicity
Periodicities refer to trends or recurring variations in element properties with increasing
atomic number
Who first arranged elements in a periodic table
Mendeleev and Meyer
What is Effective Nuclear Charge?
The amount of positive charge felt by the atom’s outer charge.
Zeff = Z - S
Z: # of protons in an atom
S: The shielding electrons
What are the trends in Atomic Size?
It decreases across the period from left to right while increases down the group.
How does a change in quantum number affect atomic size
As the principal quantum number increases the probability that the outer electron will spend more time farther from the nucleus increases as well; thus the atoms are larger
-Dominates going down a group
How does a change in Zeff affect atomic size
As the effective nuclear charge (Zeff)- the positive charge felt by
an electron increases, outer electrons are pulled closer to the nucleus thus the atom is smaller.
-Dominates going down a period
Trends in Ionic Radii in cations
A cation always has fewer electrons and the same number of protons as the parent atom; it is smaller than the atom from which it is derived.
Trends in Ionic Radii in Anions
The addition of one or more electrons to the valence shell of an atom. This results in a greater repulsion among the electron and a decrease in Zeff causing the radius of an anion to be larger than that of the parent atom.
Trends in Ionic Radii in cations across periodic table
There is a decrease se in the ionic radii of the positive ion moving
from left to right across a period in the periodic table.
Trends in Ionic Radii in anions across periodic table
Ionic radii of the negative ion moving from left to right across a period in the periodic table
What is Ionization energy?
Ionization energy is the energy required for the complete removal of 1mol of electron from 1mol of gaseous atom or ions.
What are the Trends for Ionization Energy?
-Within the period I.E increases due to decrease in atomic radius from left to right.
-While I.E decrease due to increase in atomic radius from top to bottom.
-energies always increase in the following order
-(IE₁) < (IE₂) < (IE₃) <…
What is the equation for First Ionization Energy (IE₁)
Energy + X(g)→ X⁺ + e⁻
What is the equation for Second Ionization Energy (IE₂)
Energy + X⁺(g) → X²⁺+e⁻
What is the equation for Third Ionization Energy (IE₃)
Energy + X²⁺(g) → X³⁺ + e⁻
What is Electron Affinity
The electron affinity is the energy liberated when a neutral atom adds an extra electron to itself to form a stable negative ion
What are the Trends for Electron Affinity?
What is the equation for First Ionization Energy (EA₁)
What is the equation for Second Ionization Energy (EA₂)
What is the equation for Third Ionization Energy (EA₃)
What is Electronegativity?
The measure of the relative tendency of an atom to attract electrons to itself when it is chemically combined with
another atom
What are the Trends in Electronegativity?
In general, both ionization energies and electronegativities are low for elements at the lower left of the
periodic table and high for those at the upper right
What are Isoelectric Species
Isoelectronic species are those species which have the same number of electrons and
electron configuration.
