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the smallest particle into which an element can be divided and still be the same substance. positive portion- small, massive, dense. Neutral.
a pure substance that cannot be separated or broken down into simple substances by physical or chemical means.
the tiny, extremely dense, positively charged region in the center of an atom. made up of protons and neutrons.
the negatively charged particles found in all atoms. electrons are involved in the formation of chemical bonds. they move in energy levels. 0 amu.
the positively charged particles of the nucleus. the number of protons in a nucleus is the atomic number that determines the identity of an element. 1amu.
the weighted average of the masses of all the naturally occurring isotopes of an element.
charged particles that form during chemical changes when one or more valence electrons transfer from one atom to another.
a highly organized chart listing all the known elements arranged in horizontal rows called periods and vertical columns called groups.
elements that are shiny and are good conductors of thermal energy and electric current. Most metals are malleable and ductile.
elements that have properties of both metals and nonmetals. Sometimes referred to as semiconductors.
the elements in group 1 of the periodic table. They are the most reactive metals. Their atoms have one electron in their outer level.
alkaline earth metals
the elements in group 2 of the periodic table. They are reactive metals but are less reactive then alkali metals. Their atoms have 2 electrons in their outer level.
the elements in group 17 of the periodic table. They are very reactive nonmetals, and their atoms have 7 electrons in their outer level.
the unreactive elements in group 18 of the periodic table. Their atoms have 8 electrons in their outer level. (except for helium, it has 2 electrons)
group 15. Nitrogen, phosphorus, arsenic, antimony, and bismuth. 5 electrons in the outer level.
group 16. Oxygen, sulfur, selenium, tellurium, and polonium. 6 electrons in the outer level. Reactive.
group 13. Boron, aluminum, gallium, indium, and thallium. 3 electrons in the outer level. Reactive.
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