Electron configuration Flashcards
explain electrons charge
Electrons have a
- ve charge
Overall Electrically Neutral
what makes up an atom
sub atomic particles
what is the area an electrons inhabits called
Electrons do not just move freely in the extranuclear space but are confined
to a particular region
Each of these regions are named Shells or Principal Energy Levels
formula for amount of electrons in each shell
Each shell fills to 2n*2 where
n is the number of the shell
Electrons have more energy the further away from the nucleus
why is electronic structure important?
Electronic structure is important because in principal
it can predict the reactivity of atoms and molecules!
subdivision of electronic shells
Shells are divided up into subshells labelled s, p, d and f
how are subshells numbered
Each of the subshells can be numbered and with this numbering they are classified into a specific orbital
Orbital: Region of space that can hold 2 electrons
How do we label Orbitals?
- Large number is the Shell or Principal Energy Levels
- The small letter refers to the shape
what does the letter s mean?
The letter
s means a spherical orbital.
what does the letter p mean?
The letter
p means a two–lobed orbital
-x, y, or z subscript on a p orbital label indicate
s
the coordinate axes the two lobes
what does the letter d & f mean?
The d and f orbitals has 5 and 7 differently shaped orbitals respectively
define a filled orbital
In general a filled orbital is where you will find an electron pair 90-95%
of the time
Why does an H atom have so many orbitals and only 1 electron?
Hydrogen: Why does an H atom have so many orbitals and only 1 electron?
what is an orbital
An orbital is a potential space for an electron, it can be empty
Atoms can have many potential (empty) orbitals
Previously conceived Bohr model (electrostatic, planetary model of the atom) proven by atomic emission spectra unfortunately, failed in the case of other heavier atoms
why does bohr model fail
Reason: does not predict electron-electron repulsion, other nucleus-electron attractions, also states the
electron is not allowed to occupy any of the spaces in between the orbits.
Need one more property to determine how the electrons are arranged Spin – electron spins like a top
define the pauli exclusion principle
Pauli Exclusion Principle – an atomic orbital can hold a maximum of 2 electrons and those 2 electrons must have opposite spins.
Electrons fill into equivalent energy orbitals before pairing up
Each orbital holds 2 electrons and with their spins paired
Electrons are “happy” when they are paired up in an orbital
Electrons counted like the previous two examples are in the ground state
conformation
- Atoms have a series of energy levels called Principal Energy Levels, which are
designated by whole numbers (
n = 1, 2, 3, etc.)- Principle Quantum Number
Summary: Electronic Structure of Atoms - The energy of the level increases as the value of n increases.
- Each principal energy level contains one or more types of orbitals,
called subshells - The number of subshells in a
given Principal Energy Levels
also equals n. - The
n value is always used to label the orbitals of a given principal level and
is followed by a letter that indicates the type (shape) of the orbital (
1
s, 3
p, etc.) - An orbital can be empty or it can contain one or two electrons, but never
more than two. If two electrons occupy the same orbital, they must have
opposite spins. - The shape of an orbital does not indicate the details of electron movement.
It indicates the probability distribution for an electron residing in that orbital
The orbital or, space where two electrons are found, belong to a specific shell
For example: An atom with 7 electrons fills : 2 electrons in the first shell and
5 electrons in the second shell.
In orbitals, electrons fill two into the 1s orbital, two into 2s orbital
and one into 2px, one into 2py and one into 2pz
