Chapter 3 Chem

What is the difference between an element and a compound?

An element is a pure substance with only one type of atom, while a compound consists of two or more elements chemically bonded in a fixed ratio.

What is the law of definite proportions?

A compound always contains the same elements in the same proportion by mass.

What are the two main types of chemical bonds?

Ionic bonds (transfer of electrons between metals & nonmetals) and covalent bonds (sharing of electrons between nonmetals)

What is a lattice structure?

A repeating 3D arrangement of ions in an ionic compound.

How do you name a Type I ionic compound?

Name the metal first, then the nonmetal with an -ide ending (e.g., NaCl = sodium chloride)

How do you name a Type II ionic compound?

Use Roman numerals to indicate the metal’s charge (e.g., FeCl₂ = iron(II) chloride).

What are the prefixes for naming molecular compounds?

• 1 = mono-

• 2 = di-

• 3 = tri-

• 4 = tetra-

• 5 = penta-

• 6 = hexa-

• 7 = hepta-

• 8 = octa-

• 9 = nona-

• 10 = deca-

How do you name acids?

• Binary acids (H + nonmetal) → Use hydro- + nonmetal root + -ic acid (e.g., HCl = hydrochloric acid).

• Oxyacids (H + polyatomic ion) → Change -ate to -ic acid and -ite to -ous acid (e.g., H₂SO₄ = sulfuric acid, H₂SO₃ = sulfurous acid).

How do you calculate molar mass?

Add up the atomic masses of all elements in the compound (e.g., H₂O = 2(1.01) + 16.00 = 18.02 g/mol)

What is percent composition?

The percentage by mass of each element in a compound

What must always be true in a balanced chemical equation?

The number of atoms of each element must be equal on both sides (Law of Conservation of Mass).

What are the steps to balance a chemical equation?

• List each element’s atoms on both sides.

• Adjust coefficients to balance atoms.

• Never change subscripts!

Q: What is Avogadro’s number?

6.022 × 10²³ particles per mole.

How do you convert from grams to moles?

Divide by the molar mass (grams × 1 mol/molar mass).

How do you find an empirical formula?

• Convert mass % to grams (assume 100g sample).

• Convert grams to moles.

• Divide by the smallest mole value.

• If needed, multiply to get whole numbers.

What are hydrocarbons?

Organic compounds made only of carbon (C) and hydrogen (H).

What are the three types of hydrocarbons?

• Alkanes (single bonds, -ane)

• Alkenes (double bonds, -ene)

• Alkynes (triple bonds, -yne)

What is a functional group?

A specific group of atoms that determine a molecule’s chemical behavior (e.g., hydroxyl -OH in alcohols).