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the smallest particle of an element that still retains the properties of the element


positively charged center of an atom the contains protons and neutrons and is surrounded by a cloud of electrons


particle inside of an atom that has a charge of 1+


neutral particle inside the nucleus of an atom


particle surrounding the center of an atom that has a charge of 1-

Electron cloud

area around the nucleus of an atom where the atom's electrons are most likely to be found

Atomic number

number of protons in an atom's nucleus

Atomic Mass Unit (amu)

unit of measurement for atomic particles

Mass Number

sum of the number of protons and neutrons in an atom's nucleus


atoms of the same element that have different numbers of neutrons

Average Atomic Mass

weighted-average mass of the mixture of an element's isotopes

Periodic Table

organized list of all known elements that are arranged by increasing atomic number and by changes in chemical and physical properties


vertical column in the periodic table


horizontal row in the periodic table


element that typically is a hard, shiny solid, is malleable, and is a good conductor of heat and electricity


able to be rolled of hammered into thin sheets


able to be drawn into wires


material in which electrons can move easily

Radioactive (Element)

element whose nucleus breaks down and emits particles and energy

Transition metal

metals in Groups 3 through 12 of the periodic table


first row of inner transition metals listed below the periodic table that includes a series of elements with atomic numbers of 58 to 71


second row of inner transition metals listed below the periodic table that includes a series of elements with atomic numbers of 90 to 103


element that usually is a has or brittle solid at room temperature, is not malleable or ductile, is a poor conductor of heat and electricity, and typically is not shiny


consists of two atoms of the same element


"salt former"; has seven electrons in the outer energy level

Noble gas

have eight electrons in the outer energy level; not very reactive


element that shares some properties with metals and some with nonmetals


different form of the same element having different molecular structures


materials having conductivity properties between metals (good conductors) and nonmetals (insulators) and having controllable conductivity parameters

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