Elemental Properties and Patterns

 Dimitri Mendeleev was the first scientist to publish an organized periodic table of the known elements.  He was perpetually in trouble with the Russian government and the Russian Orthodox Church, but he was brilliant never- the-less.

 Mendeleev even went out on a limb and predicted the properties of undiscovered elements.  He was very accurate in his predictions, which led the world to accept his ideas about a logical periodic table.

 Mendeleev understood the ‘Periodic Law’ which states:  When arranged by increasing atomic number, the chemical elements display a regular and repeating pattern of chemical and physical properties.

Elements are classified as:  Metals  Nonmetals  Metalloids.

 There is a zig-zag or staircase line that divides the table.  Metals are on the left of the line, in blue.  Nonmetals are on the right of the line, in orange.

 Elements that border the stair case, shown in purple are the metalloids or semi- metals.  There is one important exception. Aluminum is more metallic than not.

 How can you identify a metal?  What are its properties?  What about the less common nonmetals?  What are their properties?  And what the heck is a metalloid?

 Metals are lustrous (shiny), malleable, ductile, and are good conductors of heat and electricity.  They are mostly solids at room temp.  What is one exception?

 Nonmetals are the opposite.  They are dull, brittle, nonconductors (insulators).  Some are solid, but many are gases, and Bromine is a liquid.

 Metalloids, aka semi- metals are just that.  They have characteristics of both metals and nonmetals.  They are shiny but brittle. semiconductors  And they are semiconductors.  What is our most important semiconductor?

PERIODS Each row is called a “period” The elements in each period have the same number of shells

GROUPS Each column is called a “group” Each element in a group has the same number of electrons in their outer orbital, also known as “shells”. Except for He, it has 2 electrons valence electrons The electrons in the outer shell are called “valence electrons”

TRANSITION METALS Transition Metals have slightly different rules for shells and valence electrons. This is something you will learn about in High School Chemistry.

 Hydrogen is shown at the top of the Group 1 elements in the periodic table. The term "alkaline metal" refers to the Group 1 elements from lithium downwards and NOT hydrogen.  Hydrogen is the lightest element. It is by far the most abundant element in the universe and makes up about 90% of the universe by weight. It is also the most abundant element in the earth's sun.

DETERMINE THE NUMBER OF SHELLS AND THE NUMBER OF VALENCE ELECTRONS FOR:

Helium is the exception in Group 8. Since it has just one shell, that shell can only fit 2 electrons instead of 8. It is in this group because all the elements have a full outer shell.