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Showing posts with label Periodic Trends. Show all posts
Showing posts with label Periodic Trends. Show all posts

Wednesday, March 9, 2016

Periodic Trends on the Exam

Periodic trends were on the exam, and when I saw the first question about them I freaked out. How was I supposed to know the answer to that? There's so many trends. But, I flipped over my handy dandy periodic table and wrote out the chart that I made for trends. THATS how I'm supposed to answer those questions. It took a lot of flipping back and forth of my periodic table to my chart, but I think ultimately that is what helped me the most on the exam. Point 1 for memorization.

Electron Configuration

Examples of electron configuration...
Li
1s2 2s1

O
1s2 2s2 2p4

Ar
1s2 2s2 2p6 3s2 3p6
OR Argon (looks like) [Ne] 3s2 3p6
http://www.chemistrytutorials.org/content/atomic-structure/electron-configuration
http://chemwiki.ucdavis.edu/Core/Inorganic_Chemistry/Electronic_Structure_of_Atoms_and_Molecules/Electronic_Configurations


Electrons

2 electrons with the same spin will never occupy the same orbital...
N=1 1 Sublevel 1s Max. 2e-
N=2 2 sublevels 2s 2p max. 8e-
N=3 3 sublevels 3s 3p 3d max. 18 e-
N=4 4 sublevels 4s 4p 4d 4f max 32e-
 AUFBAU- electrons enter orbitals of LOWEST energy FIRST
PAULI EXCLUSION- an orbital can only contain TWO electrons with opposite spin
HUND'S- within a sublevel electrons enter singly before pairing up
http://education.jlab.org/qa/atomicstructure_06.html



4 Levels of Organization

1) Principal Energy Level---School Building
How far away from the nucleus an electron can be found (n)
2)Sublevel---Floor Number
(s, p, d, f)
1st principal energy level has one Sublevel, 1s
The 2nd principal energy level has 2 sublevels, 2s and 2p
The 3rd energy level has 3 sublevels, 3s, 3p, 3d
4th and all subsequent principal levels n=4s, 4p, 4d, 4f
http://w
ww.edu.pe.ca/kish/grassroots/chem/electron.htm

Trends in electronegativity

Electronegativity of an element is defined to be the tendency of an atom to draw electrons toward itself when chemically combined with another element. There are no units for this electronegativity, but it is just to be used as a comparative tool. Larger electronegativities pull electrons to themselves when bonded with other elements. Noble gases don't count when looking at electronegativity. Otherwise, electronegativity increases ⬆️➡️ The periodic table. http://www.chemguide.co.uk/atoms/bonding/electroneg.html

Periodic Trends

Again, the best way that I learn is through visuals.
Electronegativity increases ⬆️➡️ On the periodic table
Atomic Radius increases ⬇️⬅️ On the periodic table
Nonmetallic increases ↗️
Metallic increases ↙️
Electron affinity increases ⬆️➡️
Ionization energy increases ⬆️➡️ On the periodic table
http://chemwiki.ucdavis.edu/Core/Inorganic_Chemistry/Descriptive_Chemistry/Periodic_Trends_of_Elemental_Properties/Periodic_Trends