Electronic Structure of the Atom

Compliments to your arrival, readers!

We have an extremely structured read for you today!

Not getting the electronic pun?

YOU WILL SOON!

Electronic Configuration

• is the notation that describes the orbitals that electrons occupy
• also shows total number of electrons in each orbital
• helps us understand the structure of the periodic table of elements

Niels Bohr

• proposed electrons existed in specific energy levels
• when it absorbs/emits specific amount of energy it instantaneously moves from one orbital to the next

Energy Level: amount of energy an electrong of an atom can possess with 'n' the number energy levels

Quantum of Energy: energy difference between two particular energy levels

Ground State: when all electrons of an atom are in the lowest possible energy

Excited State: when one ore more of an atom's eletrons are in energy levels other then the lowest available level

Orbital: region of space occupied by an electron in a particular energy level 

Shell:  set of all orbitals having the same 'n' value

Subshell: set of orbitals of the same type

Now let's get into the meat of the lesson today!

Orbitals

• are split into 4 different types (s, p, d, f)
• each subshell consists of:
• 1 s-orbital
• 3 p-orbital
• 5 d-orbital
• 7 f-orbital
• maximum of 2 electrons can be placed into each orbit
• the maximum number of electrons in each subshell is
• 2 s-subshell
• 6 p-subshell
• 10 d-subshell
• 14 f-subshell

Electronic Configuration

This is how the orbitals are filled in for neutral atoms

1. Always start with the lowest energy level first
2. Figure out how many electrons you have (neutral atom = atomic number)
3. Start at the lowest energy level (1s) and add until nothing is left
4. Each electron has an opposite spin designated by upward and downward arrows

An example is Carbon. The last line of the picture show electronic configuration. Carbon has an atomic number of 6 = 6 electrons. The last two are not paired because when electrons occupy orbitals of equal energy, they don't pair up until they have to. 

• A good analogy of this is: when you're sitting on a bus, you don't sit beside another person until all the empty rows are taken up.
• The written form of this is 1s2 2s2 2p2

Writing Electron Configurations for Ions

For Negative Ions

• Add electrons (equal to charge) to the last unfilled subshell, starting with where the neutral atom left off

For Positive Ions

• Start with the neutral configuration, remove electrons from the outer most shell first
• If there are electrons in both the s and p-orbitals of the outermost shell
• Electrons in p-orbitals should be removed first

Core Notation

• The set of electrons for an atom can be divided into two subsections (boy do we canadians love dividing everything into sections, and even SUB-sections!)
• the core electrons
• set of electrons with configuration of the nearest noble gas before it (above it)
• normally take part in chemical reaction
• the outer electrons
• consist of all electrons outside the core
• is a way of showing the electron configuration in terms of the core and the outer electrons

1. Locate the atom and note the noble gas above the element
2. Replace the part of the electronic configuration that has the configuration of the noble gas with the noble gas symbol in brackets
3. Follow the core symbol with the electron configuration of the remaining outer electrons

• there are two notable exceptions to electronic configuration
• chromium
• 1s2 2s2 2p6 3s2 3p6 4s1 3d5
• copper
• 1s2 2s2 2p6 3s2 3p6 4s1 3d10

WHEW! That was a whole lot of information! Here is a worksheet with answers to test your knowledge!

http://misterguch.brinkster.net/PRA014.pdf