Chemistry Chapter on Resonance and Orbitals

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Questions and Answers

What is the energy of the resonance hybrid compared to the energy of contributing structures?

Equal energy

Higher energy

Lower energy (correct)

Not defined

Resonance structures can involve the movement of atoms.

False

What must all resonance structures be to be valid?

Proper Lewis structures

The more stable a structure is, the greater is its contribution to the _____ .

hybrid Signup and view all the answers

What principle states that orbitals are filled starting from the lowest energy?

Aufbau principle Signup and view all the answers

Which bond is characterized by circular symmetry when viewed along the bond axis?

Sigma bond Signup and view all the answers

Electrons in 1s orbitals have higher energy than those in 2s orbitals.

False Signup and view all the answers

What is the molecular geometry of water?

Bent Signup and view all the answers

Match the hybridization with its molecular geometry:

sp3 = Tetrahedral sp2 = Trigonal Planar sp = Linear Signup and view all the answers

What is the origin of the element carbon?

The element carbon originated in stars through nuclear fusion. Signup and view all the answers

What did Friedrich Wöhler discover in 1828?

Wöhler discovered that urea could be synthesized from ammonium cyanate. Signup and view all the answers

According to vitalism, organic compounds can only come from living organisms.

True Signup and view all the answers

What are isotopes?

Atoms with the same number of protons but different numbers of neutrons Signup and view all the answers

What determines the atomic number of an element?

The atomic number is determined by the number of protons in the nucleus. Signup and view all the answers

How many protons and neutrons are in the stable isotope 14N?

7 protons, 6 neutrons Signup and view all the answers

What is the significance of the valence electrons?

They are involved in chemical bonding. Signup and view all the answers

What is the octet rule?

Atoms tend to have eight electrons in their outer shell. Signup and view all the answers

What causes the formation of an ionic bond?

Ionic bonds form through the transfer of electrons between atoms. Signup and view all the answers

Electronegativity decreases as we move from left to right on the periodic table.

False Signup and view all the answers

Which of the following compounds is purely covalent?

F2 Signup and view all the answers

How do you determine the formal charge of an atom?

The formal charge is calculated using the formula: F = Z - (1/2)S - U. Signup and view all the answers

What are constitutional isomers?

Different compounds with the same molecular formula but different connectivity. Signup and view all the answers

What is a resonance structure?

A resonance structure is one of two or more Lewis structures representing the same molecule. Signup and view all the answers

In bond-line formulas, what does a dashed wedge represent?

A bond that projects behind the plane Signup and view all the answers

Study Notes

Resonance

The more covalent bonds a structure has, the more stable it is
Charge separation decreases stability

Atomic Orbitals and Electron Configuration

Electrons in 1s orbitals have the lowest energy because they are closest to the positive nucleus
Electrons in 2s orbitals have a higher energy level than 1s orbitals
The three 2p orbitals have equal but higher energy than the 2s orbitals
Orbitals of equal energy are called degenerate orbitals
The Aufbau principle states that orbitals are filled so that those of lowest energy are filled first
The Pauli exclusion principle states that a maximum of two electrons may be placed in each orbital but only when the spins of the electrons are paired
Hund’s rule states that when we come to orbitals of equal energy (degenerate orbitals) such as the three p orbitals, we add one electron to each with their spins unpaired until each of the degenerate orbitals contains one electron. Then we begin adding a second electron to each degenerate orbital so that the spins are paired.

Hybridization

sp3 hybridization occurs when one s and three p orbitals hybridize resulting in four sp3 orbitals
In an sp3 hybridized carbon the four sp3 orbitals are arranged in a tetrahedral arrangement
sp2 hybridization occurs when one s and two p orbitals hybridize resulting in three sp2 orbitals
In an sp2 hybridized carbon the three sp2 orbitals are arranged in a trigonal planar arrangement
sp hybridization occurs when one s and one p orbital hybridize resulting in two sp orbitals
In an sp hybridized carbon the two sp orbitals are arranged in a linear arrangement

Molecular Geometry: VSEPR Theory

The Valence shell electron pair repulsion (VSEPR) model is used to predict the molecular geometry of molecules
All valence electrons of a central atom (shared and unshared) are considered in the VSEPR model
Electron pairs tend to stay as far apart as possible, repulsive force between nonbonding pairs is greater than that between bonding pairs
The geometry of a molecule can be described by considering the positions of its atoms and not by the positions of the electron pairs

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Description

This quiz covers key concepts in chemistry regarding resonance, atomic orbitals, and electron configurations. You'll explore the stability of structures with covalent bonds, energy levels of electrons in orbitals, and important principles like Aufbau, Pauli exclusion, and Hund’s rule. Test your understanding of how these concepts interconnect to define chemical behavior.