Elements, Compounds, and Mixtures

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What are elements?

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Elements are pure substances that cannot be broken down into simpler substances by chemical means. Examples include diamonds (C) and uranium (U).

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What is a homogeneous mixture?

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A homogeneous mixture is a mixture that has a uniform composition throughout. An example is steel.

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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. For example, water (H2O) is a compound.

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What is a heterogeneous mixture?

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A heterogeneous mixture is a mixture in which the components are not uniformly distributed, and different parts can be seen. An example is a salad.

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How many molecules are in 2H2O?

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There are 2 molecules of H2O.

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What is the formula for density?

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Density is calculated using the formula: Density = mass divided by volume.

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

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

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What is an example of a pure substance?

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Examples of pure substances include elements like gold (Au) and compounds like sodium chloride (NaCl).

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What is the significance of the periodic table?

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The periodic table organizes all known elements based on their atomic number, electron configuration, and recurring chemical properties.

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What is a chemical formula?

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A chemical formula is a way of expressing the composition of a compound using symbols for the elements and numbers to indicate the ratio of atoms.