Organization of the Periodic Table

Classifying the Elements

Dmitrii Mendeleev

• Organized his periodic table by the elements increasing atomic mass

Modern Periodic Table

• The modern periodic table is organized by increasing atomic number

Periodic Law• The Periodic Law states that

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

Periods

• The horizontal rows• 1 – 7 periods• The atomic number increases

across a period from left to right

Groups• The vertical columns of the periodic table (1-18)

• All elements in a group have the same number of valence electrons

• All the elements in a group have very similar chemical and physical properties

Elements can be classified as metals,

non-metals or metalloids

Metals• Good conductors of heat and

electricity• High luster (shiny)• Malleable and ductile• Solid at room temperature (except

for Mercury)• Most elements are metals – 80%

Non-metals• Poor conductors of heat and

electricity

• Vary in properties, many are gases, some are solids and liquid

• Solid forms are dull and brittle

Metalloids• Share properties of both metals and

nonmetals

• A metalloid may behave as a metal under some conditions, but the same metalloid may behave as a nonmetal under other conditions

• Ex: May be a good conductor but brittle

Metals (left side) Non-metals (right side) Metalloids (staircase)

Metals = GreenNon-metals = BlueMetalloids = Pink

Label the following elements as a metal, non-metal, or metalloid

C = carbon Non-metal

Mg = magnesium metal

Bi = bismuth metal

Si = silicon metalloid

The periodic table consists of Representative Elements

and Transition Elements (Transition Metals and Inner

Transition Metals)

Representative Elements • Found in groups 1 - 2 and groups 13 – 18 • Wide variety of properties that represent the

table as a whole • Represent each category of metals,

nonmetals, and metalloids• Represent each state of matter solids, liquids

and gasses 13 14 15 16 173A 4A 5A 6A 7A

1A 22A

Transition metals

• Groups 3 - 12 (middle of the periodic table)• These metals are solid at room temperature

(except for Mercury)

Inner transition metals

• Found underneath the periodic table• Lanthanide series - period 6 • Actinide series - period 7 • These metals are solid at room temperature

Inner Transition Metals

Representative Elements: yellow Nobel Gasses: purpleTransition Metals: orangeInner Transition Metals: green

Important Groups

• There are groups of elements in the periodic table that are given special names

• Elements in a group share similar chemical and physical properties

Alkali Metals • Li, Na, K, Rb, Cs, Fr • Group 1 (1A) – excluding

Hydrogen• 1 valence electron• Very unstable and highly

reactive• Extremely soft metals • All have low densities, melting

and boiling points.

Alkaline Earth Metals • Be, Mg, Ca, Sr,

Ba, Ra

• Group 2 (2A)

• 2 valence electrons

• Very reactive

• Bond and lose 2 electrons

Halogens• F, Cl, Br, I, At

• Group 17 (7A)

• 7 valence electrons

• Bond and gain 1 more electron to make their outer energy level full.

• A halogens bond with alkali metals to form a salt

Noble Gasses

• Most stable of the elements (non-reactive)• Outermost energy level or shell is full, so they

do not naturally bond with other elements• Share properties like high densities, high

melting points, colorless, odorless, and tasteless

• He, Ne, Ar, Kr, Xe, Rn • Group 18 (8A)• 8 valence electrons

Lanthanide Series • “Rare-Earth elements” • Found on the top row of the inner transition

metals • Named from element Lanthanum (La) atomic

number 57 - common properties

Actinide Series • Radioactive metals • Found on the bottom row of the inner

transition metals • Named after the element Actinium (Ac)

atomic number 89 - common properties