Semester 1 Science Final Vocabulary

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presision

Back 1

how exact the measurement is

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accuracy

Back 2

the closeness of the measurementto the true value of what is being measured

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density

Back 3

the ration of mass to volume

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mass

Back 4

the amount of matter in an object

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volume

Back 5

the amount of space taken up by an object

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atom

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the smallest particle of an element

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element

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a substance that cannot be broken down into simpler substances

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compound

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a substance that is made up of two or more simpler substances and can be broken down into those simpler substances

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solution

Back 9

a mixture that forms when substances dissolve and form a homogeneous mixture

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heterogeneous

Back 10

a type of mixture in which the oarts of the mixture are noticeably different from one another

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homogeneous

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a type of mixture in which the substances are so evenly distributed that it is difficult to distinguish one from another

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isotope

Back 12

atoms of a given element that have different numbers of nuetrons and different mass numbers

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atomic number

Back 13

a unique number for each element that equals the number of protons in an atom of that element

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coefficients

Back 14

numbers that appear before a formula in a chemical equation to show the relative proportions of each reactant and product

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polyatomic

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a convalently bonded group of atoms that has a positivly or negativly charge and acts as a unit

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exothermic

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a description of a change in which a system releases energy to its surroundings

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endothermic

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a description of a change in which a system absorbs energy from its surroundings

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ionic bond

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the force that holds cations and anions togeteher

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covalent bond

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a chemical bond in which two atoms share a pair of valence electrons

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ion

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an atom or group of atoms that has a positive or negative charge

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cation

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an ion with a positive charge

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anion

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an ion with a negitive charge

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valence electron

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an electron that is in the highest occupied energy level

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buffer

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a solution that is resistant to large changes

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melting point

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the temperature at which a substance changes from a solid to a liquid

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boiling point

Back 26

the temperature at which a substance boils; the temperature at which vapor pressure is equal to atmospheric pressure

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sublimation

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the phase change in which a substance changes from a solid to a gas or vapor without changing to a liquid first

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evaporation

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the process that changes a substance from a liquid to a gas at temperatures below the substance's boiling point

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condensation

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the pahse change in which a substance changes from a gas or vapor to a liquid

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solute

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a substance whose particles are dissolved in a solution

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solvent

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a substance in which a solute dissolves

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solution

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a mixture that forms when substances dissolveand form a homogeneous mixture

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acid

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a compound that produces hydronium ions (H3O+) when dissolved in water; a proton donor

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base

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a compound that produces hydroxide ions (HO-) when dissolved in water; a proton acceptor

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pH

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a measure of hydronium ion consentration of a solution

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electrolyte

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a compound that produces ions when it dissolves