Elements, Compounds, 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 pure substance formed when two or more elements chemically combine in fixed proportions. Examples include water (H2O) and carbon dioxide (CO2).

Tags

NGSS.MS-PS1-1

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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. The components retain their individual properties. Examples include salad and air.

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What is a homogeneous mixture?

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A homogeneous mixture is a mixture in which the composition is uniform throughout. Examples include saltwater and vinegar.

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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 can be easily distinguished. Examples include a bowl of fruit and sand.

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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 does the chemical formula CO represent?

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CO represents carbon monoxide, which is a compound made of one carbon atom and one oxygen atom.

Tags

NGSS.MS-PS1-1

Front

What does the chemical formula Co represent?

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Co represents cobalt, which is a chemical element.

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What is the significance of the subscripts in a chemical formula?

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Subscripts indicate the number of atoms of each element in a compound. For example, in H2O, the '2' indicates there are two hydrogen atoms.

Tags

NGSS.MS-PS1-1

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What is an example of a physical change?

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Cutting a fruit is an example of a physical change, as it does not alter the chemical composition of the fruit.