Molecular Geometry PreLab Flashcards

Questions and Answers

What electron geometry should the central atom have when selecting from the model kit to represent the phosphorus atom in PF3? Explain why.

Trigonal Pyramid

Determine the total number of valence electrons in COF2 and show all work.

Determine the total number of valence electrons in H3O + and show all work.

Determine the total number of valence electrons in ClO3(1-) and show all work.

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What is the molecular geometry of the central atom in CH2F2? Is the molecule polar or non-polar?

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What is the molecular geometry of the central atom in COF2? Is the molecule polar or non-polar?

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Define trigonal planar.

All three repulsions on the central atom are from bonding electron densities. Signup and view all the answers

Define bent (tetrahedral).

The central atom has four electron repulsions, two bonding electron densities and two non-bonding. Signup and view all the answers

Define trigonal pyramid (tetrahedral).

The central atom has four electron repulsions, three bonding electron densities and one non-bonding electron pair. Signup and view all the answers

Define bent (trigonal planar).

The central atom has three repulsions, two bonding electron densities and one non-bonding electron pair. Signup and view all the answers

Define tetrahedral.

The central atom has four electron repulsions, all four are bonding electron densities. Signup and view all the answers

Study Notes

Lewis Structures and Valence Electrons

PF3 has a Lewis Structure where phosphorus (P) is the central atom bonded to three fluorine atoms.
The total number of valence electrons for COF2 is 24, calculated as follows: C(4x1) + O(6x1) + F(7x2).
H3O+ has a total of 8 valence electrons, calculated as: H(1x3) + O(6x1) - 1 electron for the positive charge.
ClO3(1-) totals 26 valence electrons, calculated as: Cl(7x1) + O(6x3) + 1 extra electron for the negative charge.

Molecular Geometry

The geometry for the central atom in phosphate, PF3, is trigonal pyramid due to four electron repulsions: three bonding pairs and one non-bonding pair.
CH2F2 has a tetrahedral molecular geometry; the polarity depends on the arrangement of the bonds.
COF2 also exhibits a specific molecular geometry that influences its polarity.

Electron Geometry and Types

Trigonal planar geometry involves three bonding electron densities around the central atom, resulting in even distribution.
In a bent molecular geometry (tetrahedral), there are two bonding pairs and two lone pairs, affecting the shape and polarity.
Trigonal pyramidal geometry has a central atom with three bonding pairs and one lone pair, leading to a pyramidal shape.
A tetrahedral arrangement consists solely of bonding electron pairs, resulting in a symmetrical three-dimensional shape.

Definitions of Geometries

Trigonal Planar: All three electron repulsions are from bonding pairs, leading to a flat triangular shape around the central atom.
Bent (Tetrahedral): Two bonding pairs and two lone pairs create an angular shape.
Trigonal Pyramid: Central atom has three bonds and one lone pair, forming a pyramid-like structure above the base.
Bent (Trigonal Planar): Three repulsions with two bonds and one lone pair result in a bent configuration.
Tetrahedral: All four electron pairs are bonding pairs, creating a symmetrical tetrahedral shape.

Description

Test your understanding of molecular geometry concepts with these flashcards focused on Lewis structures and electron geometry. This quiz includes questions about specific molecules like PF3 and COF2, along with their representations and geometrical shapes. Ideal for reinforcing your knowledge before a practical lab session.