Introduction to the Periodic

Table

Chapter 4.5

History of the Periodic Table

• Dmitri Mendeleev, Russian Chemist Organized the first periodic table (1860)

– Organized elements according to properties

1.Ordered by atomic mass

2.Periodic patterns

1.Arranged in vertical periods

1.Placed some elements out of

order

1.Fit into family – similar chemical

properties

2.Left openings – predicted elements

properties

2.Led to the modern periodic table

– organized by atomic number

1.Modern periodic table

1.Moseley (1911)

1.Ordered atoms by atomic number

2.Periodic law: The physical and chemical

properties of the elements are periodic functions of

their atomic numbers.

2.Periodic table: arrangement of the elements

in order of the atomic numbers so that

elements with similar properties fall in the

same group

Families & Periods

• Elements are arranged so that each vertical

column, or family, have similar physical and

chemical properties. (also called groups)

- Groups referred to as number above

column.

- Also have specific names.

• Arrange by increasing atomic number across

the row, periods.

Organization of the Periodic Table

• Periodic Table is arranged by metallic

character.

• *** Note Hydrogen is a nonmetal!

Properties of Metals • Metals (left of P.T/staircase) usually have

common properties:

• usually silver-gray (except copper and gold)

• good conductors of heat and electricity

• all but one are solid at room temperature.

• Malleable (can be bent or hammered flat)

• Ductile- can be drawn into wire

• High melting point

• Show reaction with acids

• Lustrous (shiny appearance, reflect light when polished)

Properties of Nonmetals

• Nonmetals: (found right of staircase)

• Usually dull, do not reflect light

• Brittle and cannot be hammered into sheets

• Poor conductors of electricity and heat

• Little or no reaction with acids

• Low melting points

• Either solids or gas (bromine- exception =liquid)

Properties of Nonmetals Cont.

• Most of your body’s mass is made of oxygen, carbon, hydrogen, nitrogen and phosphorus.

•Calcium, a metal, and other elements make up the remaining four percent of your body’s mass.

Metalloids/Semimetals

• Found on both sides of staircase (except Aluminum) –B, Si, Ge, As, Sb, Te, (Po book doesn’t list)

• show properties of both metals and nonmetals

• not good conductors of electricity

• When mixed with small amounts of other elements the conductivity of metalloids increase

• Silicon solid, brown or gray-black, very hard, very brittle, expands when freezes. Basis for computer chips.

• Arsenic sublimates (goes directly from solid to gas)

• Tellurium- very rare, silvery-white and poisonous

Families of the Periodic Table

Family Names

Alkali Metals

Alkaline Earth Metals

Halogens

Noble Gases

Transition Metals

Lanthanides

Actinides

Periodic Table is arranged by Families

Alkali Metals The elements in Group 1 of the periodic table are the alkali metals.

•Group 1 metals are shiny, malleable, and ductile.

•They are also good conductors of heat and electricity. However, they are softer than most other metals. (Can cut with a knife)

•The alkali metals are the most reactive of all the metals. They react rapidly, sometimes violently, with oxygen and water.

•Alkali metals don’t occur in nature in their elemental form and are stored in substances that are unreactive, such as an oil.

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Alkaline Earth Metals

• The alkaline earth metals make up Group 2 of the periodic table.

• Tarnish in air, not very hard

• Gray-white luster

•Each atom of an alkaline earth metal has two electrons in its outer energy level.

* Calcium – 5th most abundant element in Earth’s crust.

Transition Metals * Transition elements are those elements in Groups 3 through 12 in the periodic table.

•They are called transition elements because they are considered to be elements in transition between the Main Group elements.

•Transition elements are familiar because they often occur in nature as uncombined elements.

* Very hard with high melting and boiling points.

•Transition elements often form colored compounds.

•Gems show brightly colored compounds containing chromium.

* Iron makes up almost all of earth’s crust

Inner Transition Metals • The two rows of elements that seem to be

disconnected from the rest on the periodic table are

called the inner transition elements.

• They are called this because like the transition

elements, they fit in the periodic table between

Groups 3 and 4 in periods 6 and 7, as shown.

Halogens

• Halogen lights contain small amounts of bromine or iodine vapor.

• Highly reactive! High electronegativity.

• Bromine- reddish-brown liquid, metallic luster as solid, nonmagnetic, toxic and corrosive!

• All know isotopes of Iodine are radioactive, sublimates

• Astatine occurs only as result of radioactive decay of heavier elements.

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The Noble Gases

• The noble gases exist as isolated atoms.

• All gases at room temperature.

• Neon plasma glows reddish orange. Used to make signs.

•They are stable because their outermost energy levels are full.

•No naturally occurring noble gas compounds are known.

Blocks of Periodic Table

• The Periodic Table can be organized by blocks

s Block

p Block

d Block

f Block