Chemistry Problem Sets: Matter, Structure, and Energy

Vocabulary flashcards covering chemical vs. physical properties, subatomic particles, electron configurations, chemical bonding, significant figures, energy, and density/specific gravity from weekly chemistry problem sets.

Chemical Compound Formation (Sodium + Chlorine)

When sodium (a reactive metal) and chlorine (a toxic gas) react, they chemically combine to form sodium chloride ($\text{NaCl}$), which is a compound with properties completely distinct from its constituent elements.

Hypothesis

A tentative, testable explanation or proposed claim for an observation or scientific problem, such as claiming a carrot extract cures diabetes prior to rigorous experimental testing.

Physical Change

A process that alters the physical state or appearance of a substance without changing its chemical composition (e.g., making ice cubes, boiling oil, or melting lead).

Chemical Change

A process where one or more substances are transformed into chemically different substances with distinct properties (e.g., burning gasoline, rusting iron, digesting food, or synthesizing ammonia).

Chemical Symbol Rules

A proper element symbol consists of either a single capitalized letter (e.g., $\text{C}$ for carbon) or a capitalized letter followed by a lowercase letter (e.g., $\text{Ca}$ for calcium, $\text{Co}$ for cobalt). Two capital letters together (e.g., $\text{CO}$) denote a chemical compound (carbon monoxide).

Sodium Chlorate Formula

The chemical formula $\text{NaClO}_3$, representing an ingredient in herbicides composed of sodium, chlorine, and oxygen atoms in a $1:1:3$ atomic ratio.

Proton Mass

Approximately $1\,\text{amu}$ (atomic mass unit), which represents the mass of a single proton in an atomic nucleus.

Isotopes

Atoms of the same element that have the same atomic number (number of protons) but different mass numbers (number of neutrons), such as $^{12}\text{C}$ and $^{13}\text{C}$.

Ground-State Electron Configuration

The lowest-energy arrangement of electrons in the atomic orbitals of an atom or ion (e.g., lithium ($Z=3$) has the configuration $1s^2 2s^1$ or $[\text{He}]\,2s^1$).

Condensed Electron Configuration of Magnesium

Represented as $[\text{Ne}]\,3s^2$, showing the noble gas core $[\text{Ne}]$ plus the valence electrons in the $3s$ subshell for neutral magnesium ($Z=12$).

Magnesium Cation Configurations

Neutral $\text{Mg}$ is $1s^2 2s^2 2p^6 3s^2$; losing one electron gives $\text{Mg}^+$ ($1s^2 2s^2 2p^6 3s^1$); losing two electrons gives $\text{Mg}^{2+}$ ($1s^2 2s^2 2p^6$), achieving a stable noble gas core.

Nonpolar Covalent Bond

A covalent bond in which electrons are shared equally or nearly equally between two atoms of identical or similar electronegativity (e.g., $\text{C}-\text{C}$, $\text{P}-\text{H}$, $\text{S}-\text{H}$).

Polar Covalent Bond

A covalent bond between two atoms with significantly different electronegativities, resulting in unequal sharing of electrons and partial charges (e.g., $\text{C}-\text{F}$, $\text{C}-\text{Cl}$, $\text{N}-\text{O}$).

Bond Dipole Notation

The use of partial charge symbols where the less electronegative atom receives a partial positive charge ($\delta^+$) and the more electronegative atom receives a partial negative charge ($\delta^-$) (e.g., $\overset{\delta+}{\text{C}}-\overset{\delta-}{\text{Cl}}$).

Octet Rule Ionization

The process by which main-group atoms gain or lose electrons to acquire an electron configuration identical to their nearest noble gas; for example, $\text{Li}$ loses $1$ electron while $\text{S}$ gains $2$ electrons.

Significant Figures Rule for Multiplication and Division

A rule stating that the product or quotient of a calculation must contain the same number of significant figures as the measurement with the fewest significant figures.

Specific Gravity

A dimensionless ratio comparing the density of a substance to the density of water at a standard reference temperature ($1.00\,\text{g/mL}$).

Clinical Urine Specific Gravity

The normal range for urine specific gravity is $1.003$ to $1.030$; a sample with a mass of $5.36\,\text{g}$ in $5.0\,\text{mL}$ has a specific gravity of $1.07$, which is abnormally high.

Kinetic Energy

The energy possessed by an object due to its motion (e.g., a speeding train, a falling book, or an electric current moving through a lightbulb).

Potential Energy

The stored energy an object possesses due to its position, condition, or structure (e.g., water held behind a dam or a book resting on its edge before falling).

Specific Heat Capacity Equation

The heat transfer formula $q = m \cdot c \cdot \Delta T$, where $q$ is heat energy, $m$ is mass, $c$ is specific heat capacity, and $\Delta T$ is the temperature change.

Heterogeneous Mixture

A mixture that lacks a uniform composition throughout, containing visually or physically distinct phases or components (e.g., a pebble, milk).

Homogeneous Mixture

A mixture that has a uniform composition and appearance throughout its entire volume (e.g., wine, air, gasoline, bronze, sea water).