6.4 The Periodic Table and the Elements

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# 6.4 The Periodic Table and the Elements - PowerPoint PPT Presentation

6.4 The Periodic Table and the Elements. The Periodic Table and the Elements. What is the periodic table ? What information is obtained from the table ? How can elemental properties be predicted based on the PT ?.

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Presentation Transcript
The Periodic Table and the Elements
• What is the periodic table ?
• What information is obtained from the table ?
• How can elemental properties be predicted based on the PT ?

In 1869 Mendeleev and Lothar Meyer (Germany) published nearly identical classification schemes for elements known to date.

The periodic table is based on the similarity of properties and reactivity'sexhibited by certain elements.

Later, Henri Moseley ( England,1887-1915) established that each elements has a unique atomic number, which is how the current periodic table is organized.

Dmitri Mendeleev (1869)

http://www.chem.msu.su/eng/misc/mendeleev/welcome.html

Mendeleev organized his table based on multiple patterns he found, but most importantly increasing Atomic Mass.
• In order to maintain a sequential order and keep elements grouped into similar physical and chemical properties he devised an irregularly shaped table.
• He then left blanks to represent missing elements in order to maintain the pattern he had discovered.WHY?
• A missing element in his table made him believe that an element with certain properties belonged there.
Mendeleev was a genius!

Many of his predictions came true, such as the existence of “eka-aluminum” which we know as gallium.

By looking specifically for this missing “eka-aluminum”, chemists were able to discover gallium.

His predictions were quite close to the actual values of the various properties he quoted, such as mass, density, ionic formula, and others.

The Modern Periodic Table
• Today’s periodic table is based on arrangement of the elements according to ____________ atomic number.
• Henri Moseley ( England,1887-1915)
• In the periodic table, most of the elements that have atomic numbers less than 93 are ___________.
• The other elements are _______________-they have been made by scientists.

increasing

natural

synthetic

The Periodic Table
• A map of the building block of matter.

http://www.chemsoc.org/viselements/pages/periodic_table.html

The Periodic Law
• Mendeleev understood the ‘Periodic Law’ which states:
• When arranged by increasingatomic number, the chemical elements display a regular and repeating pattern of chemical and physical properties.
The Periodic Law
• Atoms with similar properties appear in groups or families (vertical columns) on the periodic table.
• They are similar because they all have the same #of valence (outer shell) electrons, which governs their chemical behavior.
3 MAJOR trends of the periodic table
• Elements are arranged by increasing…
• Atomic # or the number of Protons
• All elements in the sameFamilyor Group of the Periodic Table…
• have the same # of valence electrons
• outer shell electron configuration.
• All elements in the samePeriodof the Periodic Table…
• have the same # of shells or energy levels.

Vertical

column or Stack

Horizontal Row

Alkaline

Earth Metals

Noble

Gases

The BIG 4 Families…
• Alkali metals (1)
• Alkaline earth metals (2)
• Halogens (17)
• Noble gases (18)
Alkali Metals – Group 1
• First column on the left
• Li, Na, and K
• Shiny silver and soft
• HIGHLY REACTIVE
• Float on water
• Not often found in pure state because they easily combine with other elements
• Demo/Vid
Alkaline Earth Metals – Group 2
• Second column on the left
• Be, Mg, Ca, Sr, Ba, Rd
• Shiny silvery
• Not as soft nor as reactive as alkali metals
• Burn brightly
• Ex magnesium bright white flame
Halogens – Group 17
• Second column from the right
• Highly reactive (2nd most reactive family)
• F, Cl, Br, I, At
• Are poisonous
• Diatomic Elements (in pairs)
Noble Gases – Group 18
• Last column on the RIGHT
• Stable – non reactive
• He, Ne, Ar, Kr, Xe
• Colourless/ Odourless/ Tasteless
• Glow brightly when exposed to electrical current
• Non-toxic
• Demo
Across the Periodic Table
• Periods:Are arranged horizontally across the periodic table (rows 1-7)
• These elements have the same number of valence shells.

2nd Period

6th Period

• Nonmetals, Metals, Metalloids, Noble gases

Alkali Family:

1 e- in the valence shell

Halogen Family:

7 e- in the valence shell

Down the Periodic Table
• Family:Are arranged vertically down the periodic table (columns or group, 1- 18 or 1-8 A,B)
• These elements have the same number electrons in the outer most shells, the valence shell.
Across the Periodic Table
• Periods:Are arranged horizontally across the periodic table (rows 1-7)
• These elements have the same number of valence shells.

2nd Period

6th Period

Periodic Table: Metallic arrangement
• Layout of the Periodic Table: Metals vs. nonmetals

Nonmetals

Metals