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 substance formed when two or more elements are chemically bonded together. 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. Examples include air (a mixture of gases) and salad (a mixture of vegetables).

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How many total atoms are in K₂SO₄?

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7 (2 potassium, 1 sulfur, and 4 oxygen atoms).

Tags

NGSS.MS-PS1-1

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What is a pure substance?

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A pure substance is a material that has a constant composition and consistent properties. It can be an element or a compound.

Tags

NGSS.MS-PS1-4

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What is the difference between a homogeneous mixture and a heterogeneous mixture?

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A homogeneous mixture has a uniform composition throughout (e.g., saltwater), while a heterogeneous mixture has a non-uniform composition (e.g., salad).

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What is the law of conservation of mass?

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The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction. The total mass of reactants equals the total mass of products.

Tags

NGSS.MS-PS1-5

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What is a chemical formula?

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A chemical formula is a way of expressing information about the proportions of atoms that constitute a particular chemical compound. For example, H₂O indicates 2 hydrogen atoms and 1 oxygen atom.

Tags

NGSS.MS-PS1-1

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What is a molecule?

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A molecule is the smallest unit of a chemical compound that retains its chemical properties, consisting of two or more atoms bonded together.

Tags

NGSS.MS-PS1-1

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What is a solution?

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A solution is a homogeneous mixture of two or more substances, where one substance (the solute) is dissolved in another (the solvent).