Chapt 3: Atoms And The Periodic Table

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define Atom

Back 1

the smallest and simplest particle of an element

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define Atomic theory

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a set of assumptions proposed by the English scientist, John Dalton, to explain the chemical behavior or matter

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define Subatomic particles

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three kinds of fundamental particles from which atoms are made: protons, neutrons, and electrons

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define Proton

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a positively charged subatomic particle

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define Neutron

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an electrically neutral subatomic particle

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define Electron

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a negatively charged subatomic particle

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define Atomic mass unit (AMU

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a convenient unit for describing the mass of an atom; 1 amu= 1/12 the mass of a carbon-12 atom

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define Nucleus

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the dense, central core of an atom that contains protons and neutrons

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define Isotopes

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Atoms with identical atomic numbers but different mass numbers

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define Atomic weight

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the weighted average mass of an element’s atoms

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define Period

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one of the 7 horizontal rows of elements in the periodic table

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define Group

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one of the 18 vertical columns of elements in the periodic table

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define Main group element

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an element in one of the two groups on the left or the six groups on the right of the periodic table

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define Transition metal element

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an element in one of the ten smaller groups near the middle of the periodic table

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define Inner transition metal element

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- an element in one of the 14 groups shown separately at the bottom of the periodic table

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define Alkali metal

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an element in group 1A of the periodic table (Li, Na, K, Rb, Cs, Fr)

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define Alkaline earth metal

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an element in the group 2A or the periodic table (Be, M, Ca, Sr, Ba, Ra)

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define Halogen

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An element in group 7A of the periodic table (F, Cl Br, I, At)

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define Noble gas

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an element in group 8A of the periodic table (He, Ne, Ar, Kr, Xe, Rn)

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define (electron) Shell

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a grouping of electrons in an atom according to energy

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define (electron) Subshell

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a grouping of electrons in a shell according to the shape of the region of space they occupy

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define Orbital

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a region of space within an atom where an electron in a given subshell can be found

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define Electron configuration

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the specific arrangement of electrons in an atom’s shells and subshells

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define s-Block element

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a main group element that results from the filling of an s orbital

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define p-Block element

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a main group element that result from the filling of p orbitals

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define d-Block element

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- a transition metal element that results from the filling of d orbitals

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define f-Block element

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an inner transition metal element that results from the filling of f orbitals

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define Valence shell

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the outer most electron shell of an atom

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define Valence electron

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an electron in the valence shell of an atom

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define Electron-dot symbol

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an atomic symbol with dots placed around it to indicate the number of valence electrons

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define Triads

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a group of three elements that appear to have similar chemical and physical properties

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what are the three major classes of elements?

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Metals, nonmetals, and metalloids= three major classes of elements