The Periodic Table of Elements

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# The Periodic Table of Elements - PowerPoint PPT Presentation

The Periodic Table of Elements. Periodic  Periodic Law  Periodic Table. Something periodic occurs at regular or predictable intervals Periodic law - physical and chemical properties of the elements are periodic functions of their atomic numbers

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Presentation Transcript
Periodic  Periodic Law  Periodic Table
• Something periodic occurs at regular or predictable intervals
• Periodic law - physical and chemical properties of the elements are periodic functions of their atomic numbers
• Periodic Table of Elements – arranged by atomic number - shows patterns in properties
Element
• A pure substance made up of one kind of atom that cannot be broken down into simpler substances
• 90 occur naturally on earth
• 25 were synthesized (made) by scientists
Dmitri Mendeleev
• 1860’s
• Grouped elements together according to their atomic masses and similarities

Image taken from:

http://jscms.jrn.columbia.edu/cns/2006-04-18/fido-luxuriantflowinghair/mendeleev/

Mendeleev’s Published Periodic Table of Elements

Why do you think there are question marks here?

Image taken from: http://www.chemsoc.org/networks/learnnet/periodictable/post16/develop/mendeleev.htm

Mendeleev’s Predictions
• Mendeleev’s Table had missing elements or “gaps,” BUT he was able to predict the characteristics of these missing elements because of Periodic Law.

GermaniumActual

“Ekasilicon”

Prediction

Notice how Mendeleev’s

predictions (orange column) were very

accurate when compared to Germanium’s actual characteristics (green column)

Henry Moseley
• 1914
• Rearranged the elements by their atomic numbers
• He concluded that the number of protons in an atom is its atomic number

Image taken from:

http://dewey.library.upenn.edu/sceti/smith/

3 Classes of Elements

Using this as a guide, color code your periodic table to show the three classes. Start by highlighting the “zig-zag.”

Metals

Location

• Left of the zigzag line (exception  Hydrogen)

Chemical Properties

• Have few electrons in their outer energy level, thus lose electrons easilyMakes CATIONS Ca2+ #P > #e- Positive Charge

Physical Properties

• ductile, good conductors, malleable, shiny, most are solid @ room temperature

Image taken from:

What metal is not a solid

@ room temperature?

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Atoms with Few Electrons in their Outer Energy Level

Notice: only 1 electron in outer level

Notice: only 2 electrons in outer level

Non-Metals

Location

• Right of the zigzag line

Chemical Properties

• Almost full, or totally full outer energy levels.
• Tend to gain electrons Makes ANIONS O2- #P < #e- Negative Charge

Physical Properties

• not ductile or malleable, not shiny, poor conductors, most are solid, but some are gas at room temperature

Image taken from:

http://nobel.scas.bcit.ca/resource/ptable/cl.htm

Image taken from:

https://www.dmr.nd.gov/ndgs/rockandmineral/sulfur.asp

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Atoms with Full or Almost Full Outer Energy Level

Notice: 2 electrons in outer level – FULL

Notice: 6 electrons in outer level – almost full

Notice: 7 electrons in outer level – almost full

Metalloids

Location

• Border the zigzag line

Chemical Properties

• Most atoms have ~½ full set of electrons in outer levelMake anions or cations

Physical Properties

• have properties of both metals and non-metals

Image taken from:

http://library.thinkquest.org/C0113863/bios.shtml

Image taken from:

http://library.thinkquest.org/C0113863/bios.shtml

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Atoms with ~½ Complete Outer Energy Level

Notice: only 4 electrons in outer level

Notice: only 3 electrons in outer level

Important Features of the Periodic Table:Period (Row)
• each horizontal row of elements on the periodic table

How many

periods (rows)

are on the

Periodic Table

Of Elements?

FROM LEFT TO RIGHT OR RIGHT TO LEFT

Period Properties
• Seven periods (numbered from the top down)
• Atomic #’s and masses increase as you move from the left to the right in a period
• All elements in the same period have the same number of energy levels
• Period 1 = 1 energy level
• Period 2 = 2 energy levels
• Period 3 = 3 energy levels
• Etc…

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Examples of Period elements having the same number of energy levels in their atoms

In what period do

you think these atoms

reside?

In what period (row) do

you think these atoms

reside?

Important Features of the Periodic Table: Group (Family)

• each column of elements on the periodic table

How many groups (families)

are on the

Periodic Table

Of Elements?

FROM TOP TO BOTTOM OR BOTTOM TO THE TOP

Group (Family) Properties
• Eighteen groups (numbered from left to right)
• Atomic # and masses increase as you move from the top down in a group (family)
• Atoms of elements in the same group have the same number of valence electrons

Exceptions: Transition elements (3-12)

• Elements in groups usually have similar physical and chemical properties BECAUSE THEY HAVE THE SAME NUMBER OF VALENCE ELECTRONS

1

H

1.008

3

Li

6.941

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11

Na

22.990

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19

K

39.098

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Rb

85.468

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55

Cs

132.905

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87

Fr

(223)

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How many electrons do each of these atoms have in their outer orbital/level?

What group (family) do these elements reside in?

Identify the Element

Period 2 – Group 14 

Period 5 – Group 2 

Group 17 – Period 6 

Group 4 – Period 7 

Rutherfordium - Rf

Carbon - C

Strontium - Sr

Astatine - At