Question | Answer |
Periodic table | an arrangement of the elements in order of their atomic numbers so that elements with similar properties fall in the same column, or group. |
Noble Gas | a Group 18 element (helium, neon, argon, krypton, xenon, and radon). |
Lanthanides | one of the 14 elements with atomic numbers from 58 (cerium, Ce) to 71 (lutetium, Lu). |
Actinides | one of the 14 elements with atomic numbers from 90 (thorium, Th) to 103 (lawrencium, Lr). |
Periodicity | regular variations of properties of elements with atomic number (and position in the periodic table). |
Period | a horizontal row of elements in the periodic table. |
Family | a vertical column of the periodic table. |
Series | a horizontal row of the periodic table. |
Group | a vertical column of the periodic table. |
s-block elements | elements in Group 1 and 2, excluding H. |
p-block elements | elements in Group 13 through 18, excluding He. |
d-block metals | elements in Groups 3 through 12 with atomic numbers 21-30, 39-48, 57-80, and 89-112. |
f-block metals | elements with atomic numbers 58-71, and 90-103. |
Alkali metals | one of the elements of Group 1 of the periodic table (lithium, sodium, potassium, rubidium, cesium, and francium). |
Alkaline Earth metals | one of the elements of Group 2 of the periodic table (beryllium, magnesium, calcium, strontium, barium, and radium). |
metal | an element that is a good conductor of heat and electricity. |
transition metals | one of the d-block elements; has typical metallic properties. |
main-group or representative elements | an element in the s-block or p-block. |
halogens | one of the elements of Group 17 (fluorine, chlorine, bromine, iodine, and astatine). |
atomic radius | one-half the distance between the nuclei of identical atoms that are bonded together. |
bonding radius | the radius of the n=1 orbital in hydrogen. |
ionization energy | the energy required to remove one electron from a neutral atom of an element. |
electron affinity | the energy change that occurs when an electron is acquired by a neutral atom. |
valance electron | an electron that is available to be lost, gained, or shared in the formation of chemical compounds. |
cation | a positive ion. |
anion | a negative ion. |
ion | an atom or group of bonded atoms that has a positive or negative charge. |
atomic mass unit | a unit of mass that is exactly 1/12 the mass of carbon-12 atom, or 1.660540x10-27 kg |
nonmetal | an element that is a poor conductor of heat and electricity. |
isotope | atoms of the same element that have different masses. |
shielding effect | electrons in filled sets of s, p orbitals between the nucleus and outer shell electrons shield the outer shell electrons somewhat from the effect of protons in the nucleus; also called screening effect. |