General Chemistry Exam 1 Objectives

Element vs. Compound

An element consists of one type of atom; a compound consists of two or more bonded elements.

Atom vs. Molecule

An atom is the basic unit of an element; a molecule is two or more atoms chemically bonded together.

Subatomic Particles (Proton, Neutron, Electron)

Protons are positive (+1, 1 amu) in nucleus; neutrons are neutral (0, 1 amu) in nucleus; electrons are negative (-1, ~0 amu) outside nucleus.

Balancing Chemical Equations

Adjusting coefficients so the number of atoms for each element is equal on both sides.

Conservation of Atoms in Reactions

Atoms and subatomic particles are neither created nor destroyed during chemical reactions.

Stoichiometry Unit Interconversions

Convert between grams, moles, number of molecules, and number of atoms using molar mass and Avogadro's number.

SI Metric Prefixes

Interconvert between units using powers of ten (e.g., kilo = 10³, milli = 10⁻³, nano = 10⁻⁹).

Molar Mass Calculation

Sum the atomic masses of all atoms in a chemical formula using the periodic table.

Limiting Reactant

The reactant that is completely consumed first, limiting the amount of product formed.

Excess Reactant

The reactant that remains leftover after the limiting reactant is completely consumed.

Reaction Yield Calculations

Using stoichiometry to determine exact reactant amounts required to yield a specified product amount.

Isotope Definition

Atoms of the same element with different numbers of neutrons and different mass numbers.

Average Atomic Mass

Calculated using the sum of each isotope's mass multiplied by its fractional relative abundance.

Subatomic Particle Notation

Represent an atom/ion using its chemical symbol with mass number as superscript and atomic number as subscript.

Periodic Table Numbers and Symbols

Symbols represent elements; atomic numbers indicate protons; atomic masses indicate average mass per mole.

Periodic Table Categories

Columns are groups/families; rows are periods; elements divide into metals, non-metals, and metalloids.

Specific Periodic Families

Alkali metals (Group 1), alkaline earth metals (Group 2), halogens (Group 17), and noble gases (Group 18).

Transition and Inner Transition Metals

Transition metals occupy the d-block; lanthanides and actinides (inner transition) occupy the f-block.

Energy Minimization in Nature

Natural systems inherently seek to minimize their total energy state for maximum stability.

Coulomb's Law

Ranks energy states of charged particle systems based on particle charges and distance between them.

Electromagnetic Radiation Relationships

Wavelength and frequency are inversely proportional; energy is directly proportional to frequency.

Photon Energy Equation

Solve for photon energy using E = hc/λ or E = hν.

Photoelectric Effect

Demonstrates the particle nature of light by showing electrons are ejected only above a threshold frequency.

Photon and Quantized

A photon is a particle of light; quantized means existing only in discrete, specific energy packets.

Wave-Particle Duality

Light and electrons exhibit properties of both continuous waves and discrete particles.

Absorption vs. Emission

Absorption moves an electron to a higher energy level; emission releases a photon as it drops lower.

Principal Quantum Number (n)

Relates an electron's energy and average distance from the nucleus to its shell number (n = 1, 2, 3...).

Quantum Number Restrictions

Rules limiting values: l ranges from 0 to n-1; m_l ranges from -l to +l; m_s is +1/2 or -1/2.

Quantum Number Information

n gives energy/shell; l gives orbital shape/sublevel; m_l gives specific orbital orientation; m_s gives electron spin.

Quantum Number Assignment

Given a sublevel, supply an accepted set of quantum numbers (n, l, m_l, m_s) describing an electron within it.

Angular Momentum Quantum Number Letters

The l values 0, 1, 2, and 3 correspond to the orbital letters s, p, d, and f respectively.

Nodal Plane

A region of zero electron probability associated with the angular wave functions of orbitals.

Orbital Shapes (s, p, d, f)

s is spherical; p is dumbbell-shaped; d and f have more complex multi-lobed shapes.

Periodic Table Blocks

The periodic table blocks (s, p, d, f) correspond to the filling of respective orbital sublevels.

Sublevel Energy Ranking

Sublevels fill in order of increasing energy (e.g., Aufbau principle: 1s, 2s, 2p, 3s, 3p, 4s, 3d...).

Orbitals and Electrons per Sublevel

s has 1 orbital (2 electrons); p has 3 (6); d has 5 (10); f has 7 (14).

Quantum Numbers to Orbital Diagrams

Interconvert between quantum numbers, electron configurations, and electron energy orbital diagrams.

Electron Configurations

Write full and noble gas core electron configurations representing an atom's ground state.

Ground vs. Excited State

Ground state follows Aufbau and Hund's rules; excited state has electrons promoted to higher energy sublevels.

Unpaired Electrons and Magnetism

Unpaired electrons cause paramagnetism; all paired electrons result in diamagnetism.

Electron Configuration Exceptions

Chromium (Cr) and Copper (Cu) promote a 4s electron to half-fill or fully fill their 3d sublevels.

Valence vs. Core Electrons

Valence electrons occupy the outermost shell; core electrons occupy inner, fully-filled shells.

Electron Shielding

Inner core electrons block outer valence electrons from feeling the full positive nuclear charge.

Effective Nuclear Charge (Zeff)

The net positive charge experienced by valence electrons, increasing across a period.

Atomic Radii Trends

Atomic radius decreases across a period (due to higher Zeff) and increases down a group.

Ionization Energy Trends

Energy required to remove an electron; increases across a period and decreases down a group.

Electronegativity Trends

An atom's ability to attract shared electrons; increases up and to the right on the periodic table.

Ion Electron Configurations

Ion charges relate to periodic table groups and electron loss/gain to achieve noble gas configurations.

Cation Formation

Cations are formed by losing outermost (valence) electrons, typically from the highest n level first.

Predicting Ion Charges

Main group atoms gain or lose electrons to achieve a stable octet (noble gas configuration).

Relative Sizes of Ions and Atoms

Cations are smaller than their parent atoms; anions are larger than their parent atoms.