Measuring Matter

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Mole (mol) Noun

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[mohl]

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Mole (mol)

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The SI base unit for measuring the amount of a substance, equal to 6.02 × 10^23 representative particles.

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Example: This image shows that one mole is a specific quantity (6.022 x 10^23 particles) and connects this abstract number to a measurable mass, showing 12 grams of carbon-12 equals one mole.

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Avogadro's number Noun

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[ah-vuh-gah-drohz nuhm-ber]

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Avogadro's number

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The number of representative particles in one mole of a substance, which is approximately equal to 6.02 × 10^23.

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Example: This image shows that Avogadro's number (6.022 x 10^23 atoms) is the quantity of atoms found in exactly 12 grams of carbon.

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Representative particle Noun

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[rep-ri-zen-tuh-tiv par-ti-kuhl]

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Representative particle

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The smallest unit in which a substance naturally exists, such as an atom, molecule, or formula unit.

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Example: A water molecule is the smallest unit of water, making it the representative particle for that substance.

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Atom Noun

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[at-uhm]

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Atom

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The basic unit of a chemical element and the representative particle for elements on the periodic table.

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Example: This diagram shows an atom's structure: a central nucleus with protons and neutrons, surrounded by electrons orbiting in shells.

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Molecule Noun

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[mol-i-kyool]

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Molecule

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The representative particle for a covalently bonded compound, consisting of two or more atoms chemically joined together.

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Example: This image shows how two hydrogen (H) atoms and one oxygen (O) atom bond together to form a single water molecule (H₂O).

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Formula unit Noun

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[fawr-myuh-luh yoo-nit]

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Formula unit

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The representative particle for an ionic compound, representing the simplest whole-number ratio of ions in its structure.

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Example: This image shows the crystal lattice of salt (NaCl). A formula unit is the simplest ratio of ions in this structure, which is one Na+ for every one Cl-.

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Conversion factor Noun

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[kuhn-vur-zhuhn fak-ter]

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Conversion factor

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A ratio derived from an equality between two different units that is used to convert a quantity between units.

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Example: This image shows that 12 inches equals 1 foot and provides the formula to convert inches to feet, where dividing by 12 is the conversion.

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SI base unit Noun

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[es-ahy beys yoo-nit]

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SI base unit

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A fundamental, defined unit within the International System of Units, from which all other SI units are derived.

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Example: This chart displays the seven fundamental SI base units used for scientific measurement, showing the quantity, unit name, and symbol for each.