Exam 2 Chapter 7 Flashcards
Electron configuration:
the order of filling of orbitals;
tells us which orbitals are filled or partially filled
Core electrons
those in filled shells
“inner shell electrons”
Valence electrons:
those beyond the filled shells
“outer shell electrons”
Effective nuclear charge formula
Zeff = Z - S
How far are the electrons from the nucleus for three Noble gases (He, Ne, Ar)?
What is responsible for the differences in orbital sizes for different atoms
Electrostatic interactions
electrostatic repulsion
particles with like charges repel one another
•particles with opposite charges are attracted to each other
electrostatic attraction
What is directly related to the relative magnitudes of the charges on the particles?
The stren gth of an electrostatic attraction
is inversely related to the distance between the interacting particles
The strength of an electrostatic attraction
The potential energy of two interacting charged particles (formula)
E=potential energy of two interacting charged particles
Q=magnitude of charge
d=distance
What is responsible for the differences in orbital sizes for different atoms differences in orbital si zes for different atoms?
Electrostatic interactions
The concepts of nuclear charge, inner electron shielding and electrostatic attraction/repulsion are important in predicting what three important chemical proerties of atoms:
Atomic Size
Ionization energy
Electron affinity
Assumptions of the onion peel model
What is this really representing?
What is the border of an attom
It’s a probability boundary
What are the two ways to measrue radius of an atom?
How do you measure a Van der Waals radius?
Take the distance between 2 of the same non-touching atoms and divide by two
or subtract a known radius of one atom from the total distance
How do you mearsure a Covalent radius?
Take the distance between 2 covalently bonded atoms and divide by two
or subtract a known radius of one atom from the total distance
Why do atomic radii decrease as the period is read from left to right?
The Zeff on the valence electrons gets higher, so
the positive energy from the nucleus holds valence electrons closer.
When does atomic radii increase?
when moving right to left in a period
when moving top to bottom in a group
When does atomic radii decrease?
when moving left to right in a period
when moving bottom to top in a group
Why does atomic radii increase as groups are read from top to bottom?
There are more electrons from other energy shells taking up space.
Sodium is bigger than lithium because…
it has more electrons
Ionization energy:
The minimum energy required to remove an electron
from the ground state of the isolated gaseous atom
In context of ionizing energy: What is reported with units of kJ/mol
it is the energy required to remove one mol of electrons from one mol of gaseous atoms
What happens to the Energy required to remove e-
as we move from In to In+!?
It doubles
What happens to the Energy required to remove e-
as we move from In to In-1?
it halves
What happens to Zeff felt by departin electron
when photons begin ionizing electrons from new valence shells?
The new valence electrons no longer act as shields, so they are no longer subntracted from the atomic number to get Zeff
As atomic radius gets bigger,
ionizing energy gets smaller
As atomic radius gets smaller,
ionizing energy gets larger
As Zeff increases,
ionizing energy increases
What happens when Zeff moves down the group?
it stays constant
Where do irrecularities in first ionization energy trends appear?
2A–>3A
5A–>6A
What explains the irregularity in ionizing energy between 2A and 3A?
Orbitals of lower energy are shielding orbitals of higher energy
What explains the irregularity of electron ionization energy between 5A and 6A?
Electrons are slightly more resistent to being pulled out of a spin party
Define Electron affinity (EA)
The energy change associated with the addition of an electron to a gaseous atom or ion
What happens when E.A. is negative
(-) E.A.
What happens when E.A. is positive
(+) E.A.
What is the energy change associated with adding
one mol of electrons to one mol of gaseous atoms or ions?
1KJ/mol
What are the trends for Electron affinity?
More negative as periods move from left to right
No correlation as moving through the groups.
Why are the Electron Affiniy values for 2A positive or small negative?
a new electron would be added to an orbital of a higher energy.
Therefore, new electrons would be shaded from effective nuclear attraction.
Zeff=atomic number-shading electrons
Zeff(2A+elec)=atomic number-atomic number
Why are the Electron Affiniy values for 5A positive or “out of pattern”?
It takes extra energy to add an electron that doesn’t fit in with the dogma of the spin party.
Why are the Electron Affiniy values for Noble Gasses Positive?
They are very effectively shaded
Why doesn’t the Electron Affinity value correlate to period number?
Counteracting effects:
Being close to the atom increases electrostatic attraction to the nucleus
Being close to the atom increases electrostatic repulsion to other electrons (not enough space)
