General Chemistry Lecture 3: Chemical Bonding

Flashcards covering the fundamentals of chemical bonding, including ionic and covalent bonds, electronegativity trends, the octet rule, and the 2.0 classification rule.

How is chemical bonding defined in the lecture?

The combination of two or more atoms through rearrangement of electrons in their outer shells either by sharing of electrons or by transfer of electrons from one atom to another so that all the atoms attain the inert gas configuration of 8 electrons in their outer shells (octet rule).

What change occurs to the electron configuration of $11Na$ ($1S^2 2S^2 2P^6 3S^1$) to form a chemical bond?

It loses one electron to achieve the $10Ne$ configuration, becoming $Na^+$ ($1S^2 2S^2 2P^6$).

Which electrons are primarily involved when atoms interact to form a chemical bond?

Valence electrons, which are those in the outermost occupied shell.

What are the four types of chemical bonds listed in the notes?

1. Ionic bond, 2. Covalent bond, 3. co-ordinate bond, 4. Metallic bond.

How does ionic bonding occur?

Electrons are completely transferred from one atom to another, forming ions that are attracted to each other by electrostatic forces.

According to the factors affecting ionic bond formation, how does ionization energy relate to cation formation?

The lower the ionization energy of the metal, the easier the formation of the cation.

Where in the periodic table is ionization energy at its lowest?

As a group is descended and to the left of the periodic table; for example, the alkali metals have lowest ionization energies.

What is electron affinity?

The ability of the atom to add the electron(s) to its outer energy level.

What chemical equation represents the exothermic release of energy in electron affinity?

$$X + e \rightarrow X^- + E$$

What are the four properties of ionic compounds mentioned in the text?

1. Solid at normal conditions, 2. Crystallize in certain lattice types, 3. Dissolves in water and other polar solvents to give electrolyte solutions, 4. High melting points.

How does covalent bonding differ from ionic bonding?

Covalent bonds involve sharing of a pair of valence electrons by two atoms, whereas ionic bonds involve the transfer of electrons.

Define electronegativity.

The ability of an atom to attract electrons in a chemical bond.

What is the trend for electronegativity across a period and within a group?

It increases from left to right across a period as metallic character decreases, and within each group, it decreases with increasing atomic number and increasing metallic character.

According to the 2.0 rule, what electronegativity difference range indicates a polar covalent bond?

A range of $0.5 - 1.6$.

What electronegativity difference value is required to form an ionic bond according to the 2.0 rule?

$2.0$ or more.

Give examples of nonpolar covalent bonds provided in the notes.

$O-O$ in $O_2$, $N-N$ in $N_2$, and $C-C$ in $C_2H_6$.

Based on the provided examples, why is the bond between $K$ and $F$ classified as ionic?

The electronegativity difference between $K$ and $F$ is $3.2$, which is above the $2.0$ threshold.

Why is the bond in $HCl$ classified as polar covalent?

The electronegativity difference between $H$ and $Cl$ is $0.9$, which is small enough to qualify as polar covalent rather than ionic.