Chemistry Ch. 5 Vocab

groups

18 Vertical columns on the periodic table

periods

7 Horizontal rows on the periodic table

Electronegativity

A measure of the ability of an atom in a chemical compound to attract electrons

Anion

A negatively charged ion

Cation

A positively charged ion

Henry Moseley

Arranged the periodic table by atomic number instead of atomic mass

Dmitri Mendeleev

Created the periodic table by arranging elements in order of atomic mass, left gaps for elements he predicted would be found

valence electrons

Electrons on the outermost energy level of an atom

Alkali Metals

Group 1, 1 valence electron, very reactive, soft, silver, shiny, low density

Halogens

Group 17, 7 valence electrons, Nonmetals,Very reactive, toxic, colored

Noble Gases

Group 18, 8 valence electrons, Nonmetals, Not reactive because they have a full octet

Alkaline Earth Metals

Group 2, 2 valence electrons, harder than the alkali metals and are also less reactive

Transition Metals

Groups 3-12, shiny, good conductors of heat and electricity, high density

Lanthanides

The 14 elements with atomic numbers from 58 to 71. Rare Earth Metals

Ionization Energy

The amount of energy required to remove an electron from an atom

Ionization

any process that results in the formation of an ion

Inner Transtion Metals

appear below the main table in the f block

Fluorine

most electronegative element

Atomic Radius

one-half the distance between the nuclei of identical atoms that are bonded together; increases to the left and down

Electron Affinity

the energy change that occurs when an electron is acquired by a neutral atom

Actinides

the period below lanthanides, very unstable

periodic law

when the elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties