AP Chemistry Unit 1 Review Flashcards

Calculate quantities using dimensional analysis and the mole concept.
Avogadro’s number ( $n = 6.022 × 10^{23} \text{ mol}^{-1}$ ) connects moles to the number of particles.
Molar mass (M) is numerically equal to the average mass in amu of one particle.
Formula: $n = \frac{m}{M}$ , where:
- n = number of moles
- m = mass of the sample
- M = molar mass

Mass spectra determine the identity and relative abundance of isotopes.
Average atomic mass is estimated from the weighted average of isotopic masses.
Mass Spectroscopy separates ionized atoms/molecules using magnetic fields or voltage.
- Ionization
- Acceleration
- Deflection
- Detection

Pure substances contain either individual molecules or atoms/ions in fixed proportions (formula unit).
Law of Definite Proportions: The ratio of constituent elements' masses in a pure compound is constant.
Empirical formula: The simplest whole number ratio of atoms in a compound.

Mixtures contain two or more types of molecules/formula units with varying proportions.
Elemental analysis determines the relative numbers of atoms and the purity of a substance.

Atoms consist of negatively charged electrons and a positively charged nucleus (protons and neutrons).
Coulomb’s law calculates the force between charged particles.
Electrons reside in shells (energy levels) and subshells (sublevels), described by electron configurations.
Aufbau principle explains electron configuration.
Ionization energy relates to the distance from the nucleus and the effective nuclear charge.
Coulomb's Law: Like charges repel, opposite charges attract.
$Z_{eff} = Z – S$ where Z is the atomic number and S is the number of shielding electrons.

PES measures the energies of electrons in shells.
Peak position in PES relates to the energy required to remove an electron.
Peak height is proportional to the number of electrons in the subshell.
Photoelectric Effect: emission of electrons from a surface in response to light.
- Greater binding energy = electrons are closer to the nucleus.

Periodic table organization reflects recurring properties and electron configurations.
Trends are understood via Coulomb’s law, shell model, and shielding/effective nuclear charge.
- Ionization energy
- Atomic and ionic radii
- Electron affinity
- Electronegativity
Atomic radius:
- Decreases: left to right.
- Increases: down a group.
Ionization energy:
- Increases: left to right.
- Decreases: down a group.
Electron affinity:
- Decreases: down a group
- Increases: left to right
Electronegativity:
- Increases: left to right.
- Decreases: down a group.
Electronegativity: Ability to attract electrons.
Electron affinity: Energy released when an electron is added.