The Mole Concept

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Mole Noun

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[mohl]

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Mole

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A fundamental unit in chemistry used to measure the amount of a substance, equal to 6.02 x 10^23 particles.

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Example: This image shows that one mole is a specific quantity, defined as the number of atoms in exactly 12 grams of carbon-12.

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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 specific number of particles, approximately 6.02 x 10^23, contained in one mole of any given substance.

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Example: This image shows the specific numerical value of Avogadro's number, which is 6.02 x 10^23, the number of particles in one mole of a substance.

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Molar Mass Noun

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[moh-ler mas]

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Molar Mass

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The mass of one mole of a chemical element or compound, typically expressed in units of grams per mole.

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Example: This image shows how to find the molar mass of a water molecule (H₂O) by adding the individual atomic masses of its two hydrogen atoms and one oxygen atom.

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Particle Noun

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[pahr-ti-kuhl]

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Particle

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A general term referring to the individual units that make up a substance, such as atoms, ions, or molecules.

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Example: This diagram shows a carbon atom, a fundamental particle of matter. Atoms are the 'particles' that are counted in large groups using the mole concept.

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Standard Temperature and Pressure (STP) Noun

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[stan-derd tem-per-uh-cher and presh-er]

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Standard Temperature and Pressure (STP)

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The standardized conditions of 0 degrees Celsius and 1 atmosphere of pressure, used for comparing properties of gases.

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Example: This diagram shows that heating a fixed amount of gas in a sealed container causes its pressure to increase, as indicated by the pressure gauge.

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Standard Molar Volume Noun

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[stan-derd moh-ler vol-yoom]

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Standard Molar Volume

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The volume of 22.4 liters occupied by one mole of any ideal gas at standard temperature and pressure (STP).

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Example: This image shows that one mole of different gases (Helium, Ammonia, Oxygen), despite having different masses, all occupy the same volume of 22.4 liters at STP.

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Subscript Noun

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[suhb-skript]

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Subscript

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A number in a chemical formula indicating the quantity of atoms of an element within one molecule or formula unit.

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Example: In the chemical formula for water, H₂O, the subscript '2' indicates that there are two atoms of hydrogen (H) for every one atom of oxygen (O).

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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 numerical ratio used to express a measurement in one unit as an equivalent value in a different unit.

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Example: This diagram shows that a conversion factor is a number, like 1760, used to change one unit of measurement, like miles, into another, like yards.

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Mass Noun

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[mas]

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Mass

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A fundamental property of matter that measures its resistance to acceleration when a force is applied, often measured in grams.

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Example: This image shows a balance scale comparing a standard 1-gram weight to an apple, illustrating that mass is the amount of matter in an object.

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Grams Noun

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[gramz]

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Grams

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A metric unit of mass, commonly used in chemistry to quantify the amount of a substance in a sample.

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Example: This image compares the mass of different animals using a balance scale, introducing 'heavier' and 'lighter' and showing standard weights for 'g' and 'kg'.