Honors Chemistry Midterm Review

Quantitative Chemistry: Focuses on the measurement and calculation of chemical quantities.
Qualitative Chemistry: Involves identifying the components or characteristics of a substance without numerical measurements.
S.I. Measurements: International System of Units used for quantifying physical properties.

Density: Defined as the mass per unit volume of a substance, typically expressed in g/cm³ or kg/m³.

Chemical Change: A change that results in the formation of new chemical substances. Evidence includes color change, gas production, and formation of a precipitate.
Physical Change: A change that does not alter the chemical composition of a substance (e.g., phase changes).

Color change, gas release, temperature change, and change in odor, indicating that a chemical reaction has occurred.

Accuracy: Refers to the closeness of a measured value to a standard or known true value.
Precision: Indicates the consistency of repeated measurements, regardless of their closeness to the true value.

Direct Proportions: Two variables that increase or decrease together (e.g., if one doubles, the other doubles).
Inverse Proportions: One variable increases while the other decreases (e.g., pressure vs. volume in gas laws).
Law of Conservation of Mass: Mass is neither created nor destroyed in a chemical reaction.
Law of Definite Proportions: A chemical compound always contains its component elements in fixed ratio.
Law of Multiple Proportions: When elements combine, they do so in ratios of small whole numbers.

Atoms: Basic unit of a chemical element, consists of protons, neutrons, and electrons.
Rutherford: Proposed the nuclear model of the atom, identifying the nucleus as a dense center.
Thompson: Discovered the electron and proposed the 'plum pudding' model.
Bohr: Developed a model where electrons orbit around the nucleus in defined paths.
Atomic Number (Z): Number of protons in the nucleus.
Neutron Number: Number of neutrons in the nucleus.
Mass Number (A): Total number of protons and neutrons in the nucleus (A = Z + number of neutrons).
Nuclear Force: Strong force that holds protons and neutrons together in the nucleus.
Isotopes: Variants of a chemical element with the same number of protons but different numbers of neutrons.
Atomic Mass: Average mass of an atom of an element, measured in atomic mass units (amu).

Energy, Wavelength, Frequency: Inversely related, governed by the equations:
- $c = \lambda \, \nu$ , where $c$ is the speed of light, $\lambda$ is wavelength, and $\nu$ is frequency.
Line-emission Spectrum: Pattern of light emitted by elements when electrons fall from excited states.
Photons/Quantum of Energy: Discrete packets of energy. Energy of a photon can be calculated using Planck's equation:
- $E = h \, \nu$
- where $E$ is energy in joules, $h$ is Planck's constant (6.626 x 10⁻³⁴ Js), $\nu$ is frequency.

Max Planck: Introduced the concept of quantization of energy.
Albert Einstein: Explained the photoelectric effect, supporting quantum theory.
Quantum Numbers: Set of numbers that describe the unique quantum state of an electron. Includes:
- Principal quantum number ( $n$ )
- Angular momentum quantum number ( $l$ )
- Magnetic quantum number ( $m_l$ )
- Spin quantum number ( $m_s$ )

Modern Periodic Law: Properties of elements are periodic functions of their atomic numbers.
Periodic Table: Organized arrangement of elements:
- Group Names: Column names identifying element properties (e.g., alkali metals, noble gases).
- s, p, d, f Blocks: Designates electron sublevel filling patterns.
- Valence Electrons: Electrons in the outermost shell that determine chemical reactivity.
- Lanthanides and Actinides: Series of elements in the periodic table that include rare earth elements and actinium series, respectively.

Metals: Tend to be shiny, ductile, conductive, and malleable. Found on the left side of the periodic table.
Nonmetals: Dull, brittle, and poor conductors. Found on the right side of the periodic table.
Transition Metals: Elements characterized by the presence of d electrons.

Atomic Radius: The size of an atom, generally increases down a group and decreases across a period.
Ionic Radius: Size of an ion; cations are smaller than their parent atoms, anions are larger.
Ionization Energy: Energy required to remove an electron from an atom, increases across periods and decreases down groups.
Electronegativity: Measure of an atom's ability to attract electrons, generally increases across a period and decreases down a group.

Lewis Electron Dot Diagrams: Visual representations of valence electrons.
Bonding Types:
- Ionic Bonds: Formed through transfer of electrons from one atom to another.
- Covalent Bonds: Formed by sharing of electrons between atoms.
- Metallic Bonds: Characterized by a sea of delocalized electrons across a lattice of metal ions.
Molecular Shapes and Structures: Determined by hybridization and VSEPR theory, leading to distinct molecular geometries (e.g., linear, tetrahedral).

Classifying Equations: Identify reaction types (synthesis, decomposition, single displacement, double displacement).
Writing and Balancing Equations: Ensure mass and charge conservation in chemical equations.
- Example balancing: $Zn + H<em>2SO</em>4 \rightarrow ZnSO<em>4 + H</em>2$ (Single Displacement)

Scientific Notation: Method of expressing very large or very small numbers, represented as $N \times 10^n$ .
Significant Figures: The digits in a number that carry meaningful information about its precision.
Molar Mass: Mass of one mole of a substance, used in conversions to find moles, grams, or atoms.
Empirical Formula vs. Molecular Formula: Empirical formula gives the simplest ratio of elements, while molecular formula provides the actual number of each element in a compound.

Avogadro’s Number (Nₐ): $6.022 \times 10^{23} \, mol^{-1}$ . Represents the number of particles in one mole of a substance.
Planck’s Constant (h): $6.626 \times 10^{-34} \, Js$ . Used in calculating energy of photons.
Speed of Light (c): $3 \times 10^{8} \, m/s$ . Relationship between wavelength and frequency described by $c = \lambda \, \nu$ .