Chemistry Atomic Structure and Bonding

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Questions and Answers

What type of bond forms between nonmetals that share electrons equally?

Polar Covalent bond

Ionic bond

Nonpolar Covalent bond (correct)

Metallic bond

Ionic bonds are mostly found in a gaseous state.

False

What is the main difference between ionic and covalent bonds?

Ionic bonds involve the transfer of electrons between metals and nonmetals, while covalent bonds involve the sharing of electrons between nonmetals.

Covalent bonds do not conduct electricity because they do not have _____ free to move.

charged particles Signup and view all the answers

Match the types of bonds with their characteristics:

Covalent Bond = Sharing of electrons between nonmetals Ionic Bond = Transfer of electrons between metal and nonmetal Nonpolar Covalent Bond = Equal sharing of electrons Polar Covalent Bond = Unequal sharing of electrons based on electronegativity Signup and view all the answers

What determines the strength of lattice energy?

The size of the ions involved Signup and view all the answers

Covalent bonds result from the transfer of electrons between atoms.

False Signup and view all the answers

What is the octet rule?

Atoms tend to bond in a way that each atom has eight electrons in its valence shell. Signup and view all the answers

During an endothermic reaction, energy is ______ by the system.

gained Signup and view all the answers

Match the following terms with their definitions:

Electrostatic force = Attraction between oppositely charged particles Lewis Dot Structure = Representation of valence electrons in an atom Single bond = Sharing of one pair of electrons between atoms Lattice energy = Energy required to separate ions in an ionic compound Signup and view all the answers

Which of the following is an example of a covalent bond?

H2O Signup and view all the answers

Elements in period 3 and lower can exceed the octet rule.

True Signup and view all the answers

Name one reason why NaF has a higher lattice energy than NaI.

NaF has a smaller ionic radius than NaI. Signup and view all the answers

In a double bond, two pairs of electrons are ______ between two atoms.

shared Signup and view all the answers

What happens during the Born Haber Cycle for ionic compounds?

Energy changes are calculated at each step. Signup and view all the answers

Study Notes

Atomic Structure and Bonding

Atoms strive for the octet rule, achieving the lowest energy state.
Diatomic elements: H₂, N₂, O₂, F₂, Cl₂, Br₂, I₂ (Memorize the acronym "Have No Fear Of Ice Cold Beer")

Types of Chemical Bonds

Intramolecular Bonds: Strong bonds between atoms.
Intermolecular Bonds: Weaker bonds between molecules.

Covalent Bonds

Formed between nonmetals by sharing electrons.
Nonpolar Covalent: Equal sharing of electrons (similar electronegativity).
Polar Covalent: Unequal sharing of electrons (difference in electronegativity).
- Commonly found in all three states of matter.
- Solubility varies; some are soluble in water.
- Do not conduct electricity.
- Typically have low melting points (in liquid or gaseous phases).
Exceptions: Carbon and hydrogen always form nonpolar covalent bonds.

Ionic Bonds

Formed between a metal and a nonmetal.
Involve the transfer of electrons, forming cations (positive ions) and anions (negative ions).
- The opposite charges of the ions attract each other.
Predominantly found in the solid state.
Often soluble in water.
Conduct electricity when the charged particles are mobile (e.g., in solution or molten state).
Typically have high melting points.

Factors Influencing Bond Formation

Electronegativity: The ability of an atom to attract shared electrons in a covalent bond.
Octet Rule: Atoms tend to gain, lose, or share electrons to achieve a full outer electron shell.
Ionization Energy (IE): Measures the energy needed to remove an electron from an atom. Corresponds with electronegativity.

Lewis Dot Structures

Represent valence electrons of atoms.

Drawing Lewis Structures for Ions

Depict the gain or loss of electrons outside the bracket. (Examples given: Na, Al, Cl, and N).

Drawing Lewis Structures for Covalent Bonds

Exceptions to the Octet Rule: Hydrogen (2 valence electrons), Beryllium (4), Boron (6) Elements from period 3 and lower may have expanded octets.
Steps:
1. Determine the total valence electrons.
2. Draw the skeleton structure (hydrogen is never in the center and halogens are not usually in the center)
3. Subtract the number of electrons in bonds from the total.
4. Add lone pairs to complete octets (except for H, B, and Be).

Energy Changes

Endothermic Reactions: Absorb energy (+ΔH).
Exothermic Reactions: Release energy (-ΔH).

Lattice Energy

The energy required to separate one mole of an ionic compound into its gaseous ions.
Higher lattice energy for compounds with higher charges or smaller ionic radii.
Examples:
- Comparing Lattice Energies: Identify the compound with the largest lattice energy. (Examples provided: LiF versus NaF, NaF versus MgF2,).

Energetics of Ionic Solid Formation

The overall net energy change (sum of all energy changes) must be negative for the reaction to occur spontaneously.
Born-Haber Cycle: A cycle that illustrates the steps in forming an ionic compound and their enthalpy changes. The cycle is used to calculate the lattice energy.
Steps in the Cycle:
1. Sublimation (must be gaseous form),
2. Ionization Energy
3. Electron Affinity
4. Lattice Energy

Bond Lengths and Bond Order

Bond Length: The distance between the nuclei of two bonded atoms.
Bond Order: The number of shared electron pairs in a covalent bond.
- Single bonds have the lowest bond order, lowest bond enthalpy, and longest bond length.
- Triple bonds have the highest bond order, highest bond enthalpy, and shortest bond length.

Resonance Structures

Multiple ways of drawing the same covalent bond structure.
Often used to depict the structure that best describes a bond.

Formal Charge

A way to determine the best resonance structure by calculating the formal charge on each atom in a possible structure
The structure with the lowest formal charge is generally the best representation.

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Description

Explore the principles of atomic structure and the various types of chemical bonds in this quiz. Learn about intramolecular and intermolecular bonding, as well as the characteristics of covalent and ionic bonds. Test your knowledge and understanding of these key concepts in chemistry.