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Modern Periodic Table
Mrs. Coyle
Part I
Introduction. Periods and groups. Metals, nonmetals and metalloids.
The Modern Periodic Table
The Periodic Table is a listing of all the known elements.
The elements are organized by: Atomic number Chemical Properties
Groups and Periods
Group( or Family): a vertical column. Elements in groups have similar chemical properties.
Period: a horizontal row.
Groups and Periods are numbered.
There are 7 periods.
There are 18 numbered columns.
IUPAC
International Union of Pure and Applied Chemistry
1985 new system for labeling groups.
Metals, Nonmetals and Metalloids
Elements can be classified into:
Metals
Nonmetals
Metalloids (semimetals)
MetalsMetalloids
Nonmetals
Actinides and Lanthanides
Physical Properties of Metals
Good conductors of electricity and heat.
Malleable (can be hammered into sheets).
Ductile (can be drawn into wires). Lustrous.
Chemical Properties of Metals
Easily lose electrons.
Form positive (+) ions.
Nonmetal Physical Properties
They do not have the properties of metals.
Nonmetal Chemical Properties
Gain electrons.
Form negative ions.
Part II
Valence Electrons Group 1 Group 2
-Niels Bohr’s Model – Distinct Energy Levels
Periods
The periods (rows) of the periodic table indicate the highest energy level occupied by one or more electrons.
Valence Electrons
The electrons the occupy the highest energy level of an atom.
Valence electrons play a key role in the chemical properties of an element.
“A” Groups (Old System)
The “A” groups are numbered 18.
The number of the “A” groups correspond to the number of valence electrons.
Group 1- Alkali Metals
1 valence electron (ns1)
Form a 1+ ion.
Note: Hydrogen, a nonmetal, is located in the first column because it has one valence electron.
Group 1- Alkali Metals
Lithium
Sodium
Potassium
Rubidium
Cesium
Francium
Sodium’s Reaction with H2O Produces Hydrogen
Reactivity of Alkali Metals
Increases from top to bottom of the group.
Which is more reactive Cesium or Sodium?
Note:
Sodium and Potassium are stored in oil to keep them from reacting with oxygen and water in the air.
Cesium is stored in glass tubes of argon gas( an inert gas).
Group 2- Alkali Earth Metals
Beryllium
Magnesium
Calcium
Strontium
Barium
Radium
Group 2- Alkali Earth Metals
Have 2 valence electrons.
Form 2+ ions.
Group 2- Alkali Earth MetalsReactions with Water
Be does not react with water. Mg reacts with hot water. Ca, Sr, Ba react easily with cold
water.
Which way along the group does reactivity increase?
Notes:
There is Mg in chrolophyll
C55H72O5N4Mg
Calcium is in your bones, chalk, limestone, toothpaste, pearl (all as calcium carbonate).
The Periodic Table