Chemistry Fundamentals & Stoichiometry Flashcards

Vocabulary practice flashcards covering core chemistry topics including molar mass, stoichiometry, atomic structure, periodic trends, significant figures, chemical laws, and quantum mechanics.

Molar Mass

The mass of $1\,\text{mole}$ of a substance, expressed in units of $\text{g/mol}$.

Chemical Composition

The identity and proportion of elements present in a compound, as shown by its chemical formula detailing atom counts and ratios.

Dimensional Analysis

A method of unit conversion in which conversion factors are arranged so that unwanted units cancel out.

Density

A physical property describing how much mass is packed into a given volume, calculated using $\rho = \frac{m}{V}$.

Hypothesis

A testable explanation or prediction for a scientific question or observation.

Independent Variable

The variable in an experiment that is deliberately changed or manipulated by the investigator.

Dependent Variable

The variable in an experiment that is measured or observed to evaluate the effect of the independent variable.

Controlled Variables

The factors or conditions in an experiment that are intentionally kept constant to ensure a fair test.

Mole

A counting unit in chemistry equal to $6.022 \times 10^{23}$ particles of a substance.

Avogadro's Number

The number of representative particles contained in $1\,\text{mole}$ of a substance, equal to $6.022 \times 10^{23}$.

Percent Composition

The percentage by mass of each element in a chemical compound, given by $\%\,\text{element} = \frac{\text{mass of element in compound}}{\text{molar mass of compound}} \times 100$.

Isotopes

Atoms of the same element that have the same number of protons but different numbers of neutrons.

Proton

A subatomic particle located in the nucleus with a relative charge of $+1$.

Neutron

A subatomic particle located in the nucleus with a charge of $0$.

Electron

A subatomic particle located in the electron cloud surrounding the nucleus with a relative charge of $-1$.

Atomic Number

The number of protons in the nucleus of an atom, which uniquely identifies an element.

Mass Number

The total number of protons and neutrons in an atom's nucleus, defined as $\text{Mass number} = p + n$.

Average Atomic Mass

The weighted average mass of all naturally occurring isotopes of an element, calculated using their fractional abundances and masses.

Period

A horizontal row on the periodic table that indicates the principal energy level occupied by an atom's outer electrons.

Group

A vertical column on the periodic table containing elements that share similar chemical properties.

Alkali Metals

The chemical elements belonging to Group 1 of the periodic table.

Alkaline Earth Metals

The chemical elements belonging to Group 2 of the periodic table.

Halogens

The highly reactive chemical elements belonging to Group 17 of the periodic table.

Noble Gases

The unreactive chemical elements belonging to Group 18 of the periodic table.

Metalloids

Elements positioned along the periodic table staircase (such as B, Si, Ge, As, Sb, Te) exhibiting properties intermediate between metals and nonmetals.

Significant Figures

The digits in a measured quantity that express its precision.

Law of Constant Composition

The principle stating that a pure chemical compound always contains the exact same elements combined in the exact same mass proportions.

Law of Multiple Proportions

The principle stating that when two elements combine to form more than one compound, the masses of one element that combine with a fixed mass of the other are in simple whole-number ratios.

Orbital

A region in space around the nucleus where there is a high probability of finding an electron.

Aufbau Principle

The rule stating that electrons fill the lowest-energy orbitals first before occupying higher-energy ones.

Pauli Exclusion Principle

The rule stating that an orbital can hold a maximum of $2$ electrons, which must have opposite spins.

Hund's Rule

The rule stating that electrons occupy empty orbitals of the same sublevel individually with parallel spins before pairing up.

Valence Electrons

The electrons located in the outermost occupied principal energy level of an atom.

Cation

A positively charged ion formed when a neutral atom loses one or more electrons.

Anion

A negatively charged ion formed when a neutral atom gains one or more electrons.