The Periodic Table

Vocabulary

actinide

f-block element in period 7 of the periodic table, which consists of the elements actinium (Ac) through lawrencium (Lr)

alkali metal

element (except hydrogen) in group 1 of the periodic table

alkaline earth metal

element in group 2 of the periodic table

atomic radius

half the distance between the nuclei of two identical atoms

atomic weight

average mass of all the isotopes of an element, based on the relative abundance of each isotope

effective nuclear charge (Zeff)

net positive charge of an atom when electron shielding is considered

electron affinity

change in energy that occurs when an atom of a neutral gas gains an electron

electron shielding

decrease in attraction from the nucleus experienced by valence electrons due to the presence of inner electrons between the nucleus and the valence electrons

electronegativity

tendency of an atom to attract electrons toward itself when forming bonds

first ionization energy

energy required to remove an electron from each atom in one mole of atoms in a gaseous state, resulting in one mole of ions with a 1+ charge

group

vertical column of the periodic table

halogen

element in group 17 of the periodic table

inner transition metal

element in the f-block of the periodic table

ionization energy

energy required to remove an electron from a gaseous atom or ion

isotope

one of two or more atoms of an element that have the same number of protons but different numbers of neutrons

lanthanide

f-block element in period 6 of the periodic table, which consists of the elements lanthanum (La) to lutetium (Lu)

main group element

element in group 1, 2, or 13 to 18 of the periodic table

metal

one of a class of elements that tend to have a metallic luster, be good conductors of electricity and thermal energy, and be malleable and ductile

metalloid

one of a class of elements that tend to have properties of both metals and nonmetals

noble gas

element in group 18 of the periodic table

nonmetal

one of a class of elements that tend to not have metallic luster, be poor conductors of electricity and thermal energy, and be neither malleable nor ductile

nuclear charge (Z)

total charge of all protons within the nucleus

period

horizontal row of the periodic table

periodic law

law that states that certain chemical and physical properties of the elements recur periodically when the elements are arranged in the order of their atomic numbers

periodic table

table of all the elements arranged by atomic number into 18 vertical columns (groups) and 7 horizontal rows (periods)

second ionization energy

energy required to remove a second electron from each ion in one mole of 1+ ions in a gaseous state, resulting in a mole of ions with a 2+ charge

transition metal

element in groups 3 through 12 of the periodic table