Chapter 3: Molecules, Compounds, and Chemical Equations

A set of practice flashcards covering chemical bonds (ionic and covalent), formulas (empirical, molecular, structural), elemental forms (diatomic and polyatomic elements), molecular models, ionic compounds, and polyatomic ions based on the provided lecture notes.

What do elements do to form compounds, as illustrated by 2H2 + O2 → 2H2O?

They combine with each other (chemical bonding) to form compounds.

What are the two main classes of chemical bonds?

Ionic bonds and covalent bonds.

Between which types of elements do ionic bonds occur, and what happens to electrons?

Between metals and nonmetals; the metal loses electrons to become a cation and the nonmetal gains electrons to become an anion.

In forming table salt (NaCl), what ions are produced and how are they held together?

Na+ and Cl− ions held together by ionic bonds in a crystalline lattice.

What happens in covalent bonding?

Nonmetals share electrons; covalently bonded atoms form molecules (molecular compounds).

What is an empirical formula?

The simplest whole-number ratio of atoms in a compound.

What is a molecular formula?

The actual number of each type of atom in a molecule.

What is a structural formula?

Shows the arrangement of atoms and the bonds in a molecule.

For hydrogen peroxide, what are common representations and what do subscripts indicate?

Molecular formula H2O2; structural formula H-O-O-H; subscripts indicate how many atoms of each element are present.

What is a molecular model?

A representation of a molecule showing the relevant details; examples include ball-and-stick and space-filling models.

What are the three ways to represent a compound described in the notes?

Empirical formula, molecular formula, and structural formula.

What is the difference between empirical, molecular, and structural formulas?

Empirical shows the simplest whole-number ratio; molecular shows the actual number of atoms; structural shows the arrangement of atoms.

What is a formula unit?

The lowest whole-number ratio of ions in an ionic compound (e.g., NaCl, CaF2, Li2O, Fe2O3, CuCl).

Which elements exist as diatomic molecules? Name the seven diatomic elements.

H2, N2, O2, F2, Cl2, Br2, I2.

Which elements exist as polyatomic molecules in their elemental form?

Phosphorus (P4) and sulfur (S8).

What is a polyatomic ion?

A charged group of covalently bonded atoms (e.g., NO3−, CO3^2−, ClO−).

In NaNO3, which ions are present?

Na+ and NO3−.

In CaCO3, which ions are present?

Ca2+ and CO3^2−.

In KClO, which ions are present?

K+ and ClO−.

What are some examples of ionic compounds listed in the notes?

NaCl, CaF2, Li2O, Fe2O3, CuCl.

What is the difference between ionic and covalent bonds in terms of electron behavior?

Ionic bonds involve transfer of electrons (cation/anion formation); covalent bonds involve sharing of electrons.

What is the state and use of water at room temperature, and what is its boiling point?

Water is a liquid at room temperature; it is used to extinguish flames; its boiling point is 100 °C.