Elements, Compounds and Mixtures

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What is an element?

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An element is a pure substance that cannot be broken down into simpler substances by chemical means. Examples include hydrogen (H), oxygen (O), and gold (Au).

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What is a compound?

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A compound is a substance formed when two or more elements are chemically bonded together. Examples include water (H2O) and carbon dioxide (CO2).

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What is a mixture?

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A mixture is a combination of two or more substances that are not chemically bonded. Examples include air (a mixture of gases) and salad (a mixture of vegetables).

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What is the difference between a pure substance and a mixture?

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A pure substance has a uniform and definite composition, while a mixture contains two or more substances that retain their individual properties.

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What is condensation?

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Condensation is the process by which water vapor in the air cools and changes into liquid water, forming droplets. An example is the water droplets on a cold glass.

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What is evaporation?

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Evaporation is the process by which liquid water turns into water vapor. This occurs when heat is applied to the liquid.

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What is sublimation?

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Sublimation is the process where a solid changes directly into a gas without passing through the liquid state. An example is dry ice (solid carbon dioxide) turning into gas.

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What is the formula for density?

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Density = mass divided by volume (D = m/V).

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What is the process of melting?

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Melting is the process of changing a solid into a liquid by adding heat.

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What is the volume of an object?

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Volume is the amount of space an object occupies, typically measured in cubic centimeters (cm³) or liters (L).