Lecture 30: Chemical Bonding (Ch 11) - The Lewis Structure Part II

These flashcards encompass key concepts and principles related to VSEPR theory and molecular geometry, as discussed in Lecture 30.

What is the Valence Shell Electron Pair Repulsion (VESPR) theory?

VESPR theory states that electron groups around a central atom repel each other, affecting the molecular geometry.

What defines an electron group in a Lewis structure?

An electron group can be a lone pair, single bond, double bond, or triple bond around the central atom.

How many electron groups does nitrogen have in NH3?

Nitrogen in NH3 has 4 electron groups: 3 single bonds and 1 lone pair.

What is the molecular geometry of a molecule with four electron groups and no lone pairs?

The molecular geometry is tetrahedral.

How do lone pairs affect molecular geometry?

Lone pairs exert greater repulsion than bonding pairs, modifying bond angles and overall shape.

What is the bond angle in a tetrahedral shape?

The bond angle in a tetrahedral shape is approximately 109.5 degrees.

What shape is formed when there is one lone pair among four electron groups?

The shape is trigonal pyramidal.

Describe the effect of lone pairs on bond angles.

Lone pairs decrease bond angles due to greater repulsion compared to bonding pairs.

What is the molecular geometry when there are two lone pairs on a central atom with four electron groups?

The geometry will be bent.

How does increasing the number of lone pairs impact molecular shape?

Increasing lone pairs leads to increased repulsion and altered molecular shapes.

What geometry is observed with 5 electron groups and 1 lone pair?

The geometry is seesaw.

When there are 2 lone pairs around a central atom with 5 electron groups, what is the result?

The geometry is T-shaped.

What arrangement does a central atom have if it has 6 electron groups and no lone pairs?

The arrangement is octahedral.

How are 3D molecular geometries represented on paper?

3D structures are depicted using wedges and dashes to show atoms in different planes.

Can you predict molecular geometry for larger molecules with multiple central atoms?

Yes, by applying VSEPR principles to each central atom individually.

What is a key takeaway about depicting molecules with different atomic planes?

If all atoms are in the same plane, there are no dashes or wedges; different planes require these indicators.

What is the electron-group geometry for a central atom with two electron groups?

The electron-group geometry is linear. This arrangement means that the two electron groups are 180 degrees apart from each other.

What is the molecular geometry and bond angle for a molecule with two electron groups and no lone pairs?

The molecular geometry is linear, and the bond angle is 180 degrees

What is the electron-group geometry for a central atom with three electron groups?

The electron-group geometry is trigonal planar.

What is the molecular geometry and bond angle for a molecule with three electron groups and no lone pairs?

The molecular geometry is trigonal planar, and the bond angle is 120 degrees

What molecular geometry results from a central atom with three electron groups and one lone pair?

The molecular geometry is bent, with a bond angle less than 120 degrees