Chemistry Midyear Exam Review

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describes a relationship in nature that is supported by many experiments

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scientific law

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explanation supported by many experiments, still subject to new experimental data, can be modified

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scientific theory

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scientific notation

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express numbers as a multiple of two factors

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accuracy

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refers to how close a measured value is to an accepted value

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precision

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refers to how close a series of measurements are to one another, precise measurements show little variation over a series of trials but many may not be accurate

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ability of inability of a substance to combine with or change into one or more new substances

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chemical property

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characteristic of matter that can be observed or measured without changing the samples compostition

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physical property

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physical property that remains the same no matter how much substance is present

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intensive property

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physical property that is dependent upon the amount of substance present

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extensive property

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states that in any chemical or physical process, energy may change from one form to another but is neither created nor destroyed

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law of conservation of energy

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mass is neither created nor destroyed during a chemical reaction but is conserved

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law of conservation of mass

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states that, regardless of the amount, a compound is always composed of the same elements in the same proportion by mass

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law of definite proportions

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mixture that does not have uniform composition without

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heterogeneous mixture

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mixture that has a uniform composition without

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homogeneous mixture

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states that when different compounds are formed by the combination of the same elements, different masses of one element combine with the same mass of the other element in a ration of small whole numbers

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law of multiple proportions

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mixture of elements that has metallic properties, most commonly forms when the elements are either similar in size

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alloy

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pure substance that cannot be broken down into simpler substances by physical or chemical means

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element

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smallest particle of an element that retains all the properties of that element, is electrically neutral spherically shaped, and composed of electron, protons, and neutrons.

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atom

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negatively charged, fast-moving particle with an extremely small mass that is found in all forms of matter and moves through the empty space surrounding an atom's nucleus

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electron

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subatomic particle in an atom's nucleus that has a positive charge of 1+

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proton

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neutral subatomic particle in an atom's nucleus that has a mass nearly equal to that of a proton, 1+

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neutron

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chemical combination of two or more different elements, can be broken down into simpler substances by chemical means and has properties different from those of its component elements

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compound

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chart that organizes all known elements into a grid of horizontal rows (periods) and vertical columns (families) arranged by increasing atomic number

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periodic table

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states that when the elements are arranged by increasing atomic number, there is a periodic repetition of their chemical and physical properties

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periodic law

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particle with two protons and two neutrons, with a 2+ charge, equivalent to a helium-4 nuclleus

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alpha particle

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radiation that is made up of alpha particles; is deflected toward a negatively charged plate when radioactive source is deflected between two electrically charged plates

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alpha radiation

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high-speed electron with a 1-charge that is emitted during radioactive decay

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beta particle

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radiation that is made up of beta particles; is deflected toward a positively charged plate when radiation from a radioactive source is directed between two electrically charged plates

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gamma rays

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spontaneous process in which unstable nuclei lose energy by emitting radiation

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radioactive decay

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atom or bonded group of atoms with a positive or negative charge

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ion

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electrostatic force that holds oppositely charged particles together in an ionic compound

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ionic bond

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atoms of the same same element with the same number of protons but different numbers of neutrons

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isotopes

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rays and particles- alpha and beta particles and gamma rays- that are emitted by radioactive materials

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radiation

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form of energy exhibiting wavelike behavior as it travels through space; can be described by wavelength, frequency, amplitude, and speed and includes visible light, microwaves, x rays, and radio waves

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electromagnetic radiation

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set of frequencies of electromagnetic waves given off by atoms of an elent; consists of a series of fine lines of individual colors

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atomic emission spectrum

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1/12 the mass of a carbon-12 atom

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atomic mass unit

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a 3-D region around the nucleus of an atom that describes and electron's probable location

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atomic orbital

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minimum amount of energy that can be gained or lost by an atom

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quantum

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a particle of electromagnetic radiation with no mass that carries a quantum of energy

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photon

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a phenomenon in which photoelectrons are emitted from a metal's surface when light of a certain frequency shines on the surface

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photoelectric effect

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lowest allowable energy state of an atom

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ground state

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states that it is not possible to know precisely both the velocity and the position of a particle at the same time

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heisenberg uncertainty principle

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consists of an element's symbol, representing the atomic nucleus and inner-level electrons, that is surrounded by donts, representing the atom's valence electrons

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electron-dot structure

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the arrangement of electrons in an atom, which is prescribed by three rules-aufbau principle, pauli exclusion principle and hund's rule

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electron configuration

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states taht each electron occupies the lowest energy orbital available

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aufbau principle

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states that a maximum of two electrons may occupy a single atomic orbital, only if the electrons have opposite spins

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pauli exclusion principle

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states that single electrons with the same spin must occupy each equal-energy orbital before additional electrons with opposite spins can occupy the same orbital

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hund's rule