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Electrons-Particles that have a negative electric charge.

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Electrons-Particles that have a negative electric charge.

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Atomic Number- The number of protons in an atom (and the number of electrons).

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Atomic Number- The number of protons in an atom (and the number of electrons).

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Mass Number-The number of protons plus the number of neutrons.

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Mass Number-The number of protons plus the number of neutrons.

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Isotopes-Atoms of the same element that have different numbers of neutrons.

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Isotopes-Atoms of the same element that have different numbers of neutrons.

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Compound-Atoms of more than one type of element that are chemically bonded together.

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Compound-Atoms of more than one type of element that are chemically bonded together.

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Molecule-A group of atoms connected by a covalent bond

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Molecule-A group of atoms connected by a covalent bond

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Mixture-Two or more substances that are not chemically combined.

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Mixture-Two or more substances that are not chemically combined.

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Heterogeneous Mixture-A mixture which is not mixed evenly and each component retains its own properties.

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Heterogeneous Mixture-A mixture which is not mixed evenly and each component retains its own properties.

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Homogeneous Mixture-A mixture which is evenly mixed throughout.

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Homogeneous Mixture-A mixture which is evenly mixed throughout.

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Solution-Another name for a homogeneous mixture.

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Solution-Another name for a homogeneous mixture.

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Density-The mass of an object divided by its volume.

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Density-The mass of an object divided by its volume.