GENERAL CHEMISTRY THE ESSENTIAL
CONCEPTS RAYMOND CHANG EXAM
PREPARATION PACK 2026 KEY CONCEPTS
AND REVISION NOTES
◉ What is the periodic trend for atomic mass? Answer: Increases left
to right across a period and increases top to bottom down a group.
◉ What is the periodic trend for reactivity in metals? Answer:
Increases going down a group.
◉ What is the periodic trend for reactivity in nonmetals? Answer:
Increases going up a group.
◉ What are the four types of chemical bonding? Answer: 1. Metallic
bonding, 2. Ionic bonding, 3. Molecular covalent bonding, 4.
Extended covalent bonding.
◉ Describe metallic bonding. Answer: Positively charged atomic
cores surrounded by a delocalized sea of valence electrons.
,◉ Describe ionic bonding. Answer: Metal atoms lose valence
electrons to become cations; nonmetals gain electrons to become
anions.
◉ Describe molecular covalent bonding. Answer: Nonmetal atoms
share valence electrons in covalent bonds, forming discrete
molecules.
◉ Describe extended covalent bonding. Answer: Valence electrons
shared in covalent bonds extending across the material.
◉ Why are ionic solids brittle? Answer: When stressed, layers shift
causing like charges to line up, leading to repulsion.
◉ What is noble gas envy? Answer: The tendency of atoms to gain,
lose, or share electrons to achieve a full valence shell.
◉ What are the HONC 1234 rules? Answer: Hydrogen forms 1 bond,
Oxygen forms 2 bonds, Nitrogen forms 3 bonds, Carbon forms 4
bonds.
◉ What is the Lewis structure procedure? Answer: 1. Count total
valence electrons. 2. Arrange non-H atoms. 3. Add H's. 4. Add lone
pairs. 5. Recount.
, ◉ What are isomers? Answer: Molecules with the same molecular
formula but different structural formulas.
◉ What is a lone pair? Answer: A pair of valence electrons on an
atom that is not shared.
◉ What is bond order? Answer: The number of bonding pairs of
electrons shared between two atoms.
◉ What are resonance contributors? Answer: Multiple valid Lewis
structures for the same molecule with different electron positions.
◉ What is formal charge? Answer: Formal charge = (# valence e⁻
alone) - (# bonds) - (# non-bonding e⁻).
◉ What does VSEPR stand for? Answer: Valence Shell Electron Pair
Repulsion.
◉ What geometry results from 2 electron domains? Answer: Linear;
bond angle ≈ 180°.
◉ What geometry results from 3 electron domains? Answer:
Trigonal planar (0 lone pairs) or bent (1 lone pair); approximate
bond angles 120°.
CONCEPTS RAYMOND CHANG EXAM
PREPARATION PACK 2026 KEY CONCEPTS
AND REVISION NOTES
◉ What is the periodic trend for atomic mass? Answer: Increases left
to right across a period and increases top to bottom down a group.
◉ What is the periodic trend for reactivity in metals? Answer:
Increases going down a group.
◉ What is the periodic trend for reactivity in nonmetals? Answer:
Increases going up a group.
◉ What are the four types of chemical bonding? Answer: 1. Metallic
bonding, 2. Ionic bonding, 3. Molecular covalent bonding, 4.
Extended covalent bonding.
◉ Describe metallic bonding. Answer: Positively charged atomic
cores surrounded by a delocalized sea of valence electrons.
,◉ Describe ionic bonding. Answer: Metal atoms lose valence
electrons to become cations; nonmetals gain electrons to become
anions.
◉ Describe molecular covalent bonding. Answer: Nonmetal atoms
share valence electrons in covalent bonds, forming discrete
molecules.
◉ Describe extended covalent bonding. Answer: Valence electrons
shared in covalent bonds extending across the material.
◉ Why are ionic solids brittle? Answer: When stressed, layers shift
causing like charges to line up, leading to repulsion.
◉ What is noble gas envy? Answer: The tendency of atoms to gain,
lose, or share electrons to achieve a full valence shell.
◉ What are the HONC 1234 rules? Answer: Hydrogen forms 1 bond,
Oxygen forms 2 bonds, Nitrogen forms 3 bonds, Carbon forms 4
bonds.
◉ What is the Lewis structure procedure? Answer: 1. Count total
valence electrons. 2. Arrange non-H atoms. 3. Add H's. 4. Add lone
pairs. 5. Recount.
, ◉ What are isomers? Answer: Molecules with the same molecular
formula but different structural formulas.
◉ What is a lone pair? Answer: A pair of valence electrons on an
atom that is not shared.
◉ What is bond order? Answer: The number of bonding pairs of
electrons shared between two atoms.
◉ What are resonance contributors? Answer: Multiple valid Lewis
structures for the same molecule with different electron positions.
◉ What is formal charge? Answer: Formal charge = (# valence e⁻
alone) - (# bonds) - (# non-bonding e⁻).
◉ What does VSEPR stand for? Answer: Valence Shell Electron Pair
Repulsion.
◉ What geometry results from 2 electron domains? Answer: Linear;
bond angle ≈ 180°.
◉ What geometry results from 3 electron domains? Answer:
Trigonal planar (0 lone pairs) or bent (1 lone pair); approximate
bond angles 120°.
