Empirical and Molecular Formulas

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Empirical Formula Noun

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[em-peer-i-kuhl for-myuh-luh]

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Empirical Formula

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A chemical formula showing the simplest whole-number ratio of moles of the elements present in a compound.

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Example: This table shows how a molecule's actual formula (Molecular Formula) is simplified to its simplest whole-number ratio of atoms (Empirical Formula).

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Molecular Formula Noun

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[muh-lek-yuh-ler for-myuh-luh]

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Molecular Formula

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A chemical formula that specifies the actual number of atoms of each element in one molecule of a substance.

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Example: This image shows a methane molecule, which has 1 carbon and 4 hydrogen atoms, matching its molecular formula, CH₄, which counts these atoms.

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Percent Composition Noun

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[per-sent kom-puh-zish-uhn]

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Percent Composition

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The percentage by mass of each element present within a chemical compound, indicating its elemental makeup.

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Example: This example calculates the percent composition of a molecule by dividing each element's mass by the total molecular mass, then multiplying by 100.

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Empirical Evidence Noun

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[em-peer-i-kuhl ev-i-duhns]

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Empirical Evidence

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Information and data acquired through observation or experimentation, which serves as the basis for scientific knowledge.

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Example: This diagram shows the scientific method, a process where empirical evidence is gathered through observation and experiments to test a hypothesis and draw conclusions.

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Analytical Chemist Noun

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[an-l-it-i-kuhl kem-ist]

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Analytical Chemist

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A chemist who analyzes substances to determine their composition, structure, and the quantity of each component.

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Example: This image lists different types of analytical chemistry, like food or environmental analysis, but doesn't explain what an analytical chemist actually does.

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Synthetic Chemist Noun

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[sin-thet-ik kem-ist]

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Synthetic Chemist

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A chemist who specializes in the creation of new chemical compounds through planned chemical reactions and processes.

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Example: A synthetic chemist combines simpler molecules, like hydrogen and oxygen, to create new, more complex molecules, such as water (H2O).

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Gravimetric Analysis Noun

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[grav-i-me-trik uh-nal-uh-sis]

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Gravimetric Analysis

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A quantitative chemical analysis method involving the measurement of the mass of a substance, typically a solid precipitate.

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Example: This diagram shows the laboratory equipment used for gravimetric analysis, a method to separate and weigh a solid precipitate to determine a substance's composition.

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Volumetric Analysis Noun

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[vol-yoo-me-trik uh-nal-uh-sis]

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Volumetric Analysis

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A quantitative chemical analysis method involving the measurement of the volume of a solution of known concentration.

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Example: This diagram shows the laboratory setup for volumetric analysis, where a burette is used to add a measured volume of a solution to a conical flask.

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Hydrocarbon Noun

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[hahy-droh-kahr-buhn]

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Hydrocarbon

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An organic chemical compound that is composed exclusively of hydrogen and carbon atoms, forming its fundamental structure.

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Example: This image shows the structure of simple hydrocarbons like ethane and propane, which are molecules made only of hydrogen (H) and carbon (C) atoms.

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Formula Unit Noun

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[for-myuh-luh yoo-nit]

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Formula Unit

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The simplest whole-number ratio of cations to anions represented in an ionic compound's crystal lattice structure.

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Example: This image shows one sodium ion (Na+) and one chloride ion (Cl-), representing the formula unit of salt (NaCl), the simplest whole-number ratio of ions.