Theory Unit 2 - Trends & Electron Configuration Flashcards
Atomic Size
Size of an atom.
Depends on the number of energy levels and the overall charge of the nucleus (the nucleus’s charge depends on the number of protons).
As you go down a group you are adding energy levels (rings around the nucleus) so the atomic size increases.
As you go across a period the atomic size decreases because the energy levels (which contain negative electrons) are increasingly attracted to the positive protons in the nucleus of the atom.
Electronegativity
Tendency of an atom to attract electrons to itself when it combines with another element.
Electronegativity increases from left to right across a period on the periodic table.
Electronegativiy decreases as you go down a group on the periodic table.
Bond Pairs
Pairs of electrons which form a bond.
Lone Pairs
Electron pairs which are not involved in bonding. They do however, affect the shape because electron pairs repel other electron pairs.
Rules for Writing Lewis Dot Structures
- Total the Valence Electrons and Update during each step.
- Form a single bond between the central atom and each surrounding atom (each bond uses two electrons).
- Place electrons around the outer atoms until you run out or they each have eight electrons around them. (Hydrogen and Helium can only have two electrons around them).
- Place any remaining electrons around the central atom.
- Does each atom other than hydrogen have eight electrons around it?
- Rearrange (share) electrons so that all atoms other than hydrogen have eight electrons around them.
Octet Rule
All atoms other than hydrogen and helium bond to fill their valence shell with eight electrons.
Duet Rule
Hydrogen bonds to fill it’s valence shell with two electrons. Helium already has two electrons and thus does not need to form bonds to increase stability.
Violations of the Octet Rule
Be - 4
B - 6
P - 8 or 10
S - 8, 10, or 12
Xe - 8, 10, or 12
VSPER
Valence Shell Electron Pair Repulsion
Most important aspect of determining the shape or geometry of a molecule. The molecule will adopt the shape which minimizes te electron pair repulsion.
Which of the following elements has the largest atomic radius?
A. nitrogen B. oxygen C. fluorine D. neon
N
(least number of protons attracting the electrons on the energy levels)
Which has the largest atomic radius?
K
Na
Rb
Li
Rb
(most energy levels)
Which has the smallest atomic radius?
A. fluorine B. chlorine C. bromine D. iodine
F
(least number of energy levels)
Which has the highest electronegativity?
Na
Al
S
Cl
Cl
Which has the lowest electronegativity?
F
I
Br
Cl
I
What is the Lewis dot structure of Br₂?
What is the Lewis dot structure of XeF₄?
What is the Lewis dot structure of [NO₂]‾¹?
What would the Lewis dot structure of OC be?
Photon
Energy given off in the form of light by an excited electron. Otherwise known as a “quanta of light”.
Sublevel
Principal energy levels are broken down into sublevels designated s, p, d, or f upon which electrons travel.
Orbital
Sublevels can be broken down into regions called “orbitals”. An orbital is defined as the most probable location for finding an electron. Each orbital holds 2 electrons.
Quantum of Energy
Absorbed when an electron moves from its ground state to its excited state.
Electron Configuration
A shorthand method of writing the location of electrons by sublevels.
Photon
Energy given off in the form of light by an excited electron. Otherwise known as a “quanta of light”.
Sublevel
Principal energy levels are broken down into sublevels designated s, p, d, or f upon which electrons travel.
Orbital
Sublevels can be broken down into regions called “orbitals”. An orbital is defined as the most probable location for finding an electron. Each orbital holds 2 electrons.
Orbital Diagram
Shorthand method of writing the location of electrons by orbital.
Pauli Exclusion Principle
If there are two electrons in an orbital, they must have opposite (paired) spins.
Hund’s Rule
When filling sublevels other than s, electrons are placed in individual orbitals before they are paired up.
Electrons fill like people do on a bus. You would never sit right next to someone you do not know if there are free seats available, unless of course all the seats are taken then you must pair up.
So, when working with the p sublevel, electrons fill like this…up, up, up….down, down, down…
Quantum of Energy
Absorbed when an electron moves from its ground state to its excited state.
What element is represented by this orbital diagram?
Carbon
What is the orbital diagram for Magnesium?
What is the orbital diagram for Sulfur?
What is the orbital diagram for Oxygen?
What is the orbital diagram for Nitrogen?
What is the orbital diagram for Silicon?
What element is represented by the following orbital diagram?
Fluorine
What element is represented by the following orbital diagram?
P (Phosphorus)
What is the electron configuration of Krypton?
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶
[Ar] 4s² 3d¹⁰ 4p⁶
What is the electron configuration of Zinc?
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰
[Ar] 4s² 3d¹⁰
What is the electron configuration of Vanadium?
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d³
[Ar] 4s² 3d³
What is the electron configuration of Calcium?
1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
[Ar] 4s²
What is the electron configuration of Beryllium?
1s² 2s²
