Liquids And Solids

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Kinetic-Molecular Theory Noun

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[ki-net-ik-mo-lek-yuh-ler thee-uh-ree]

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Kinetic-Molecular Theory

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A model explaining the behavior of matter by considering the motion of its particles and the forces between them.

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Example: This diagram shows that matter is made of particles whose movement (kinetic energy) increases with temperature, changing the state from solid to liquid to gas.

Front

Incompressible Adjective

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[in-kuhm-pres-uh-buhl]

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Incompressible

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A property of a substance that resists being compressed, meaning its volume changes very little under applied pressure.

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Example: This diagram shows that particles in solids and liquids are packed closely together, leaving little space for compression, making them incompressible.

Front

Fluidity Noun

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[floo-id-i-tee]

Back

Fluidity

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The ability of a substance, such as a gas or a liquid, to flow and to diffuse.

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Example: This diagram shows that in a liquid, particles are close but not in fixed positions, allowing them to slide past one another, which is why liquids can flow.

Front

Viscosity Noun

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[vis-kos-i-tee]

Back

Viscosity

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A measure of the resistance of a liquid to flow, determined by intermolecular forces, particle shape, and temperature.

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Example: This image compares how water, oil, and honey flow to show different levels of viscosity, which is a liquid's resistance to flowing.

Front

Surface Tension Noun

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[sur-fis ten-shuhn]

Back

Surface Tension

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The energy required to increase the surface area of a liquid, caused by the net inward pull on surface particles.

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Example: This diagram shows that liquid molecules inside are pulled in all directions, but molecules at the surface are pulled only inwards, creating a tight "skin".

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Surfactant Noun

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[sur-fak-tnt]

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Surfactant

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A compound that lowers the surface tension of a liquid, such as water, by disrupting intermolecular bonds.

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Example: A surfactant molecule has a 'water-loving' (hydrophilic) head and a 'water-hating' (hydrophobic) tail, allowing it to connect water with oils and dirt.

Front

Cohesion Noun

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[koh-hee-zhuhn]

Back

Cohesion

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The intermolecular force of attraction that exists between identical molecules within a substance.

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Example: This diagram shows how water molecules, which are all the same substance, stick together because of an attraction called a hydrogen bond.

Front

Adhesion Noun

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[ad-hee-zhuhn]

Back

Adhesion

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The intermolecular force of attraction that occurs between molecules that are different from each other.

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Example: This diagram shows water moving up a thin glass tube. This happens because water molecules are attracted to the glass (adhesion), causing them to 'stick' to and climb the tube's surface.

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Meniscus Noun

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[muh-nis-kuhs]

Back

Meniscus

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The curved upper surface of a liquid in a tube, caused by the interplay between cohesive and adhesive forces.

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Example: This diagram shows that a meniscus is the curved upper surface of a liquid in a tube, and that you must read the volume from the bottom of the curve.

Front

Capillary Action Noun

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[kap-uh-ler-ee ak-shuhn]

Back

Capillary Action

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The upward movement of a liquid within a narrow tube, resulting from adhesive and cohesive forces working together.

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Example: Water moves up a narrow tube against gravity because the forces of adhesion (water sticking to the tube) are stronger than cohesion (water sticking to itself).