16 terms

Atomic Structure and the Periodic Table 2016

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mass number
the sum of the atom's protons and neutrons in the nucleus
atomic number
the number of protons in the atom's nucleus; determines the chemical properties of an element and its place in the periodic table.
proton
positively charged part of the atom; located within the nucleus
neutron
particle with no charge; found inside of the nucleus
electron
negatively charged part of the atom; found outside of the nucleus
ion
an atom in which the number of protons does not equal the number of electrons
net charge
an atom has a positive net charge if it has lost negative electrons and has more positive protons. It has a negative net charge if it has gained electrons
Groups
Also called Families on the Periodic table; are arranged in vertical columns (up and down)
Periods
Also called Rows on the Periodic Table; are arranged horizontally (left to right)
Mendeleev
Arranged the first Periodic Table and discovered the periodic law
Moseley
discovered that every element's identity is determined by its number of protons
valence electrons
found in the atom's outermost energy level
halogens
are reactive nonmetals found in Group 17 of the Periodic Table; Fluorine, Chlorine, Bromine, Iodine, and Astatine
noble gases
gases found in Group 18 of the Periodic Table; usually nonreactive with other elements
alkali metals
highly reactive metals found in Group 1 of the Periodic Table (Lithium, Sodium, Potassium, Rubidium, Cesium, Francium)
alkaline earth metals
reactive metals found in Group 2 of the Periodic Table (Beryllium, Magnesium, Calcium, Strontium, Barium, and Radium)