Unit 4 Chemistry Test

Lavoisier

The guy who compiled a list of 33 elements organized into four categories

Newlands

Arranged the elements by atomic mass

Law of octaves

Properties repeat every 8th element

Mendeleev

Made first periodic table, arranged by increasing atomic mass

Moseley

Arranged the elements in order of atomic number

Representative Elements

Tall columns (s and p blocks), follow rules and patterns

Transition Elemtents

Short columns (d block), does not follow patterns as well and contains many exceptions to the rules

Horizontal rows

Periods, similar size

Vertical Columns

Groups/ families, similar properties, same number of valence electrons

IIA

Alkali earth metals

VIIA

Halogens

VIIIA

Noble Gasses

Atomic radius

Distance from the center of the atom to the outermost electron

Atomic Radius Increases

Increases down and left

Ionization Energy

The energy needed to remove an electron

Ionization energy increases

Increases up and right

Electronegativity

The tendency for an atom to attract electrons when combined with other atoms

Electronegativity Increases

Up and right (E)

Reactivity

Tendency of an element to undergo a specific reaction

Radioactivity Increases

Down