Flashcards- Ch 2 Basic Chemistry

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Element

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A substance that cannot be broken down into other substances by chemical reactions. Found on the Periodic Table.

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Example of an Element

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Carbon (C) and Oxygen (O)

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Examples of importance of elements to living organisms

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Enlarged thyroid glands caused by iodine deficiency in humans.

Discoloration of leaves affecting overall health of plant due to nitrogen deficiency.

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Molecule

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A pure substance composed of one or more different elements combined in a fixed ratio. Examples include O₂, N₂, and H₂O. These ratios give them unique properties.

NOTE: All compounds are molecules but not all molecules are compounds. Ex: Water is both a molecule and a compound since it satisfies both definitions, but O₂ is a only a molecule since a compound must involve more than one type of element in its chemical make-up.

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Compound

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A pure substance composed of two or more different elements combined in a fixed ratio. Examples include NaCl and H₂O. Compounds have unique properties beyond those of the combined elements.

NOTE: all compounds are molecules but not all molecules are compounds.

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Atom

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The smallest unit of matter that retains the physical and chemical properties of its element.

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Proton

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Charge: +
Location: Nucleus

# of protons identifies the element on the periodic table

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Neutron

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Charge: 0 (none)

Location: Nucleus

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Electron

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Charge: -
Location: Electron cloud

Electrons are used to form chemical bonds

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Atomic number

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The number of protons in an atom of an element. All atoms of an element have the same atomic number.