Arrangement of the Periodic Table

halogen

Any element in Group 17 - F, Cl, Br, I, and At

noble gas

Any element in Group 18 - He, Ne, Ar, Kr, Xe, and Rn

alkaline earth metal

Any element in Group 2 - Be-Mg, Ca, Sr, Ba, and Ra

main group element

Any element in Groups 1,2, 13-18

alkali metal

Any metal in Group 1 - Li, Na, K, Rb, Cs, Fr

Dmitri Mendeleev

Arranged elements by increasing atomic mass, arranged columns of elements by similar properties, and left spaces for undiscovered elements.

Henry Moseley

Arranged periodic table by increasing atomic number.

periodic table

Chart of all elements arranged in columns in such a way that all of the elements in a given column exhibit similar chemical properties or in rows in such a way that all of the main group elements exhibit a set of repeating properties.

metal

Element characterized by the ability to conduct heat and electricity, and a tendency to be shiny, malleable and ductile.

nonmetal

Element characterized by the lack of ability to conduct heat or electricity, and a tendency to be dull, colorful, and brittle.

metalloid

Elements exhibiting both metallic and nonmetallic character - B, Si, Ge, As, Sb, and Te.

period

Horizontal in the main body of the periodic table.

group

Vertical column on the periodic table. Also called family.

periodic law

When elements are arranged by increasing atomic number, there is a periodic repetition of physical and chemical properties.