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chapter one
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Gravity
Terms in this set (29)
Bohr model of the atom
shows electrons moving in specific orbits around the nucleus
wavefunctions
we now view the shapes and properties of atomic orbitals as they are obtained from basic quantum mechanics through solution of the Schrodinger equation termed wavefunctions.
they correspond to atomic or molecular orbitals
principal quantum number
assigned by the quantum mechanical model to indicate the relative sizes and energies of atomic orbitals
valence shell
determined by the highest principal quantum number
-typically the only electrons involved in bonding
azimuthal quantum number
The second quantum number. Designated by the letter l, it means "angular momentum" and refers to the subshell (s, p, d, f, etc.) in which the given electron resides. l can take on the value of an integer in the 0 to n-1 range.
- describes the spatial distribution of the orbital with respect to the nucleus
node
the principal quantum number 2 has s and p orbitals. the 2s orbital is similar to the 1s orbital but has a spherical surface in three-dimentional space where the electron density goes to zero, called a node
- a surface ( a sphere for s orbitals, a plane for p orbitals) that separates the positive and negative regions of a wavefunction
there is zero probability of finding an electron at an orbital node
2p nodal plane
a p orbital can orient along three perpendicular directions in space
- the 2p orbitals have a nodal plane that contains the nucleus and its perpendicular to the orbital axis
magnetic quantum number
symbolized by m, indicates the orientation of an orbital around the nucleus
- the directionality of an orbital in space
-for p the numbers are (-1,0,and 1) each representing one of three different orthogonal directions in space
phasing
a result of the mathematical functions describing the orbitals
electron density/distribution
the probability of finding an electron in the differently phased regions.
- related to the square of mathematical function that represents the orbitals
m_s
associated with the spin of an electron (+1/2 or -1/2)spin paired
-these movements are correlated to keep like charges apart
correlation
the ability of an electron to feel the trajectory of another electron and therefore alter its own course so as to minimize Coulombic repulsions and keep energy of the system to a minimum
1.1.2 ELECTRON CONFIGURATIONS AND ELECTRONIC DIAGRAMS
...
electron configuration
the arrangement of electrons of an atom in its ground state into various orbitals around the nuclei of atoms
Ground state of carbon
1s^2 2s^2 2p^2
-the most stable form
exited state of carbon
promotion of an electron from an atomic orbital to a higher-lying atomic orbital produces a higher energy state
1s^@ 2s^1 2p^3
electronic diagram
the atomic orbitals are represented by horizontal lines at different energy level, where the higher the line on the page the higher the energy
-symbols are placed near the lines to indicate which orbitals the lines are meant to represent
Aufbau Principle
states that each electron occupies the lowest energy orbital available
Pauli Principle
atomic orbitals can hold only 2 electrons at most and they must have opposite spins
Hund's Rule
states that single electrons with the same spin must occupy each equal-energy orbital before additional electrons with opposite spins can occupy the same orbitals
octet rule
States that atoms lose, gain or share electrons in order to acquire a full set of eight valence electrons
valence number
the number of bonds an atom can make
1.1.3 Lewis structures
allows us to use valence electrons of atoms in a molecule to predict the bonding in that molecule
-the problem with lewis structures is that they provide no insight into molecular shapes, orbitals, or distributions of electrons withing molecules
-only really useful for predicting the number of bonds an atom actually forms
formal charge
The number of valence electrons in an isolated atom minus the number of electrons assigned to the atom in the Lewis structure
how realistic are formal charges?
formal charge is more or less a bookkeeping tool
however it is possible to develop a more precise description of the electron distribution using more sophisticated techniques
VSEPR theory
Valence-shell electron-pair repulsion theory; because electron pairs repel, molecules adjust their shapes so that valence electron pairs are as far apart as possible
sterics
a notion associated with the through space repulsion between two groups
steric repulsion
arises from the buttressing of filled orbitals that cannot participate in bonding ,where negative electrostatic field of the electrons in the orbitals is repulsive
Hybridization
the method of adding and subtracting atomic orbitals on the same atom
- remember th
ex. Figure 1.2
;