The Periodic Table

Chapter 12 Lesson 2Pages E14 – E21

Objectives

• Recognize that the elements are organized according to their properties in a chart called the periodic table of the elements.

• Recognize that there are more than 100 known elements, and each can be identified by its symbol.

• Observe that elements are grouped into three “classes”: metals, nonmetals, and semimetals.

450 B.C.

• Greek philosopher Empedocles (ehm PEHD uh kleez) all matter made up of four elements– Earth– Air– Fire– Water

1600’s

• English chemist, Robert Boyle, argued earth, air, fire, and water could not be real elements.

1700’s

• French chemist, Antoine-Laurent Lavoisier\

• Made one of the first modern lists of chemical elements

1800’s

• Many new elements being identified• Scientist realizing some elements

had similar properties• Began organizing elements into

families, or groups, with similar properties

• Still no standardized way of classifying elements

1869

• Russian chemist Dmitri Mendeleyev

• Developed a way to arrange and classify elements

Mendeleyev arrangement

• FIRST– Listed the

elements in order of increasing mass

– Noticed a repeating pattern

• NEXT– Rearranged the list

so elements with similar properties would appear in the same columns of his table

– He left empty spaces for future elements that were discovered

PERIODIC TABLE

• A table in which the elements are arranged by their properties

• The periodic table is standardized– This means scientist all over the world

use the same one

Why is the table called periodic?

• Mendeleyev discovered the properties of elements have a repeating pattern

• The word periodic means “repeating”

The modern periodic table arranges the elements by

their?

• properties

The Periodic Table

• Modern periodic table elements are arranged in order of increasing atomic number

• This means= the number of protons in their nuclei

Understanding the table

• Each element box:– Lists the atomic number– Chemical symbol (abbreviation of the

element’s name, sometimes from Greek or Latin)

– Name– Often included is also the mass

Understanding the Table

• Each Column:– Called a group– They have similar properties

– Look at copper (Cu), silver (Ag), and gold (Au) on page E17

– These three elements are all soft, shiny metals

Understanding the Table

• Horizontal Rows:– Called periods

– They have an increasing number of elements

– Two rows are pulled out to keep the table from getting to long

Classification of Elements

• METALS – are usually shiny, can be bent or stretched, and conduct electricity

• NONMETALS – most are gases. Solid nonmetals are usually dull in color, do not conduct electricity, do not bend or stretch, and break

• SEMIMETALS – have characteristics of metals and nonmetals

Look at the periodic table page E17

• Can you find a pattern of metals, nonmetals, and semimetals in the table?

• Do you think an element found on the bottom left-hand side of the periodic table is a metal, a semimetal, or a nonmetal?

• Most metals are found on the lower left-hand side of the table, so I would say probably a metal

Chemical symbols are different colors

• The color of the symbol tells you if the element is a solid, liquid, or gas at room temperature

• Most are solids

METALS

• Properties:

– Luster – the ability to reflect light– Bendable by force or heating– Can be stretched or pulled into thin

wires– Conduct electricity

Metals

• Found in your body and foods• Bones & teeth calcium• Blood iron• Most metals found in living things

combine with other elements in chemical compounds

SEMIMETALS

• Have properties of both metals and nonmetals

• Silicon is a semimetal• 28% of Earth’s crust is silicon 2nd

most common element• Sand a compound of silicon &

oxygen

Silicon

• A semi-conductor• Under some circumstances silicon

conducts electricity and at other times it does not

• Adding elements to silicon changes its conductivity

• Silicon is used to make electric circuits found in computer chips

NONMETALS & Nobel Gases

• Solid nonmetals do not conduct electricity and dull in color

• They are brittle (break easy)• Example is Sulfur• Sulfur used in car batteries• Phosphorus – the striking surface

of safety matches is a nonmetal

Nonmetal gases

• Nitrogen – 78% of the air you breath

• Oxygen – most abundant element on earth: 21% of air you breath and 47% Earth’s crust

• Combines with many metals• RUST – combination of iron &

oxygen

Last column of periodic table

• NOBEL GASES – rarely combine with other elements to form compounds

• Helium – lighter than air• Will glow if an electric current is

passed through them – Used to make neon signs

A _____________ is made of two or more elements combined chemically.

• Compound

______________ are elements that rarely combine with other elements to form

molecules.• Nobel Gases

Elements are arranged by properties in the _______________

• Periodic table

_______________ are usually shiny and bendable.

• Metals

An element’s ________________ is an

abbreviation of its name, sometimes from Latin or

Greek.• Chemical symbol

In the periodic table a column is called a____________.

• group

What requires a chemical reaction to form?

• A compound

List three properties of metal.

• Shiny, reflect light, bendable, stretchable, able to conduct electricity and heat