Chemistry Lecture Review: Chemical Bonds, Molecular Geometry, & Intermolecular Forces

Flashcards covering chemical bonds, ions, molecular geometry, electronegativity, and intermolecular forces from the lecture notes.

How are ionic bonds formed?

Ionic bonds are formed when valence electrons are transferred from one atom to another.

How are covalent bonds formed?

Covalent bonds are formed when valence electrons are shared between atoms.

How is the charge of an atom or ion determined?

The charge is determined by the number of protons minus the number of electrons.

What happens to metal atoms and nonmetal atoms during ion formation?

Metal atoms typically lose electrons to become cations with a positive charge, while nonmetal atoms gain electrons to become anions with a negative charge.

When is a Roman numeral included in the name of a metal ion?

A Roman numeral is included when there is more than one ionic form of the metal (e.g., Iron(II) ion for Fe^2+), but not if there is only one ionic form (e.g., silver ion for Ag^+).

What is a polyatomic ion?

A polyatomic ion is an ion derived from a molecule, rather than a single atom, and has a unique name, formula, and charge.

What do prefixes like 'di-' and 'mono-' indicate in a molecule's name?

Prefixes indicate the number of each type of atom in the molecule (e.g., 'di-' for two, 'mono-' for one).

What are the key characteristics of ionic compounds?

Ionic compounds result from electron transfer, have a net charge of zero, their ratio of cations to anions is reflected in subscripts, and they exist as a lattice structure.

List the diatomic elements.

The diatomic elements are H2, N2, O2, F2, Cl2, Br2, and I2.

What is the Octet Rule?

The Octet Rule states that atoms form bonds to achieve eight electrons in their valence energy levels, with hydrogen being an exception, forming one bond to obtain two electrons.

What do ball-and-stick models depict compared to Lewis dot structures?

Ball-and-stick models depict molecular geometry and bond angles, while Lewis dot structures show the arrangement of atoms, bond types, and nonbonding electrons.

What is the difference between electron geometry and molecular geometry?

Electron geometry is the relative position of electron groups (bonds and lone pairs) on the central atom, while molecular geometry is the relative position of only the atoms in the molecule, influenced by lone pairs.

What are the electron geometries for 2, 3, and 4 groups of electrons around a central atom?

Two groups: linear; Three groups: trigonal planar; Four groups: tetrahedral.

How are bonds represented on paper to depict molecular geometry?

A straight line for bonds in the plane of the paper, a hashed line for bonds projecting into the paper, and a wedge for bonds projecting out of the paper.

What is electronegativity?

Electronegativity is a measure of an atom’s ability to draw electrons toward its nucleus when part of a covalent bond.

Which element is the most electronegative?

Fluorine, with an electronegativity of 4.0.

How does electronegativity change within a group of the periodic table?

It increases from left to right on the periodic table, left side is bigger, right side is smaller

How is the polarity of a covalent bond determined?

The polarity of a covalent bond is determined by the difference in electronegativity between the two atoms that form the bond.

What ranges of electronegativity difference classify bonds as nonpolar, polar covalent, or ionic?

Nonpolar bond: difference between 0 and 0.4; Polar covalent bond: difference between 0.5 and 1.9; Ionic bond: difference of 2.0 or higher.

What are intermolecular forces (IMFs) of attraction, and how do they compare to intramolecular forces?

Intermolecular forces are attractions between molecules in the solid and liquid phases. They are much weaker than intramolecular forces (covalent or ionic bonds), typically 5% to 10% of their strength.

What physical properties of a compound are determined by intermolecular forces?

Intermolecular forces determine physical properties such as boiling point, melting point, and solubility.

What are the three types of intermolecular forces of attraction found in pure compounds?

The three types are dispersion forces, dipole-dipole forces, and hydrogen bonding forces.

Describe dispersion forces.

Dispersion forces are the weakest type of intermolecular force, found in all compounds but are the only IMF in nonpolar compounds. They are caused by temporary molecular dipoles created by momentary shifts of electrons.

What are dipole-dipole forces?

Dipole-dipole forces are intermolecular forces of attraction that occur between the opposite partial charges of permanent dipoles in polar molecules.

What is required for hydrogen bonding to occur?

Hydrogen bonding, the strongest type of IMF, occurs in molecules containing one of the three strongest bond dipoles: H-F, H-O, or H-N bonds.

How do lone pairs of electrons on a central atom typically affect molecular polarity?

Lone pairs of electrons often create an uneven distribution of electron density, making the molecule polar.

How do intermolecular forces affect a compound's boiling point?

Stronger intermolecular forces require more energy to overcome, resulting in a higher boiling point for the compound.