Unit 2b: Light and the Periodic Table
Electromagnetic Radiation/ Light:
Here is the Power Point used in class to go over electomagnetic radiation. Again, the PowerPoint alone is not very helpful; notes are required to follow along.
All Videos
All Videos
IDTIMWYTIM: Schrodinger's Cat
Dr Quantum - Double Slit Experiment
IDTIMWYTIM: Radiation
Organizing the Electron Cloud!
Electron Configurations
Electron configurations are a way of writing down how electrons are organized within the electron cloud. The number out front tells you the energy level those electrons are in. The letter tells you the sublevel within that energy level which the electrons are held. The superscript tells you the number of electrons being held in each sublevel. When writing electron configurations, read the periodic table left to right and top to bottom.
ex: Ge
The Periodic Table!
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Periodic Trends
Shielding = when core electrons block the pull (of nucleus) on valence electrons
Effective Nuclear Charge (Zeff) = the pull of the nucleus on the valence electrons
increases
decreases
As you move to the right, the shielding remains the same but the number of protons increases. The more protons in the nucleus, the stronger it's positive charge and attraction to the valence electrons.
As you move down the periodic tabe, the shielding increases and takes on the charge of the nucleus. This causes the positive charge to be distributed through more electrons so it it weaker on the outside, valence electrons.
You can try to picture Zeff this way: .
As you move down a group you increase the number of protons (the lenght/strength of the atoms arms) but you also increase the number of electrons it has to cary. As you continue to add rows of electrons, the atom has a harder time holding onto its valence electron. In this example, lithium has a nice handle on its valence electron where cesium has to carry and reach around all of its core electrons.
As you move to the right, the shielding (rows of electrons the atom has to cary) stays the same but the number of protons increases. This means the positive force (or the atoms arms) are much stronger and can hold onto the valence electrons better.
Atomic Radius = size
decreases
increases
Atomic Radii of Ions
ca+ion = a positive ion; loss of electrons
-as atoms lose electrons they shrink in size
anion = a negative ion; gain of electrons
-as atoms gain electrons they grow in size
-For more information click on the link:
Ionization Energy= the energy needed to remove an electron
As you move to the right, the effective nuclear charge (Zeff) increases meaning the valence electrons are held tigher by the nucleus. As this pull by the nucleus increases, it is harder to take away an electron so it requires more energy....more ionization energy!! Also, as you move to the right the atom gets closer to the octet rule (8 electrons) so the atom does NOT wananything to take electrons away.
increases
decreases
As you move down the periodic tabe, the shielding increases and takes on the charge of the nucleus. This causes the atom to be larger in size and for the effective nuclear charge to be weaker. This means the atom has a weaker hold on it's valence electrons, so requires less energy to take an electron (it gets easier to take an electron)
Electronegativity= the ability of an atom to attract a bonding pair of electrons
*exclude the Noble Gases
As you move to the right, the valence electron count becomes closer to eight so it's easier for atoms to gain electrons than lose them (to become stable).
increases
decreases
As you move down the periodic tabe you increase the number of energy levels. This means you increase the distance from the nucleus (larger size) so the effective nuclear charge (Zeff) is weaker and less able to hold another electron.
Metallic Characteristic= having properties of metals [reflect light(luster), malleable, ductile, conductor...]