Chemistry Basics

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Anion

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A negatively charged ion, formed when an atom gains one or more electrons. Example: Chloride ions (Cl^-) are anions found.

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Cation

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A positively charged ion, formed when an atom loses one or more electrons.
Example sentence: Sodium ions (Na⁺) are cations found in table salt.

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Covalent bond

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A type of chemical bond where two atoms share electrons.
Example sentence: The water molecule (H₂O) is held together by covalent bonds between hydrogen and oxygen atoms.

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Chemical Reaction

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A process that involves the rearrangement of atoms and molecules, resulting in the formation of new substances.
Example sentence: Burning wood is a chemical reaction that releases heat and light.

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Excess reagent

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A reactant that is present in a larger amount than needed for a complete reaction.
Example Sentence: If you have more baking soda than vinegar, the baking soda is the excess reagent.

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Hydrate

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A compound that contains water molecules within its structure. Example Sentence: Copper sulfate pentahydrate (CuSO₄·5H₂O) is a hydrate that contains five water molecules per copper sulfate molecule.

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Ionic bond

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A type of chemical bond formed by the electrostatic attraction between oppositely charged ions.
Example sentence: Table salt (NaCl) is held together by ionic bonds between sodium cations (Na⁺) and chloride anions (Cl^-).

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Molar mass

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The mass of one mole of a substance, expressed in grams per mole (g/mol).
Example sentence: The molar mass of water (H₂O) is 18.015 g/mol.

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Mole

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A unit of measurement in chemistry that represents a specific number of particles (6.022 x 10²³).
Example Sentence: One mole of carbon atoms contains 6.022 x 10²³ carbon atoms.

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Molecule

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A group of two or more atoms held together by chemical bonds.
Example sentence: A water molecule (H₂O) is made up of two hydrogen atoms and one oxygen atom.