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periodic table
atoms and the periodic table
Term | Definition |
---|---|
atom | the smallest particle into which an element can be divided and still be the same element |
electron | negatively charged particles that are outside the nucleus in the electron cloud |
nucleus | small, dense, center that has a positive charge and is surrounded by moving electrons |
proton | positively charged particles in the nucleus |
neutron | particles in the nucleus that have no charge |
electron cloud | area around the nucleus in which electrons move |
atomic number | the number of protons in the nucleus of an atom |
mass number | total number of protons and neutrons in an atom's nucleus |
periodic table | an arrangement of the elements in order from increasing atomic mass |
average atomic mass | the average of the masses of all the naturally occurring isotopes of that element |
metalloid | elements that have some properties of metals and some properties of nonmetals |
chemical symbol | an abbreviation of the element where the first letter is always capitalized and all other letters are lower case |
metal | elements that are shiny, and conduct heat and electricity well, malleable, and ductile |
group | vertical column of elements that have similar physical and chemical properties |
nonmetal | elements that are poor conductors, dull, and brittle |
period | horizontal row of elements |
chemical bond | interactions that holds atoms or ions together |
valence electron | electrons found in the outermost energy level |
ion | a particle with a positive or negative charge |
ionic bond | force that brings oppositely charged ions together: metal and nonmetal |
covalent bond | atoms share one or more pairs of electrons: nonmetals |
molecule | group of atoms held together by chemical bonds |
metallic bond | formed between metal atoms when their outermost energy levels overlap |