Semester 1 Review

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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 oxygen (O), hydrogen (H), and carbon (C).

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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. An example is sugar (C12H22O11).

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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 and salad.

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What is a main sequence star?

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A main sequence star is a star that is in the stable phase of its life cycle, where it fuses hydrogen into helium in its core. An example is Vega.

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What happens in the Northern Hemisphere during winter?

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When it is winter in the Northern Hemisphere, it is summer in the Southern Hemisphere.

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What is the difference between a compound and a mixture?

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A compound is a chemical combination of elements, while a mixture is a physical combination of substances that retain their individual properties.

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What is an example of an element?

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An example of an element is uranium (U), which is a pure substance that cannot be broken down.

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What is the chemical formula for sugar?

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The chemical formula for sugar is C12H22O11.

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What is the classification of water (H2O)?

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Water (H2O) is classified as a compound because it consists of two hydrogen atoms chemically bonded to one oxygen atom.

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What is the significance of the main sequence in stellar evolution?

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The main sequence is significant because it represents the longest phase in a star's life cycle, where it spends most of its time.