LECTURE                             PERIODIC TABLE

In this lecture you will learn:

Once many of the elements were known scientists started grouping them by certain characteristics or properties
 
5 CLASSES OF ELEMENTS
click on the LINK to see the periodic table for each

METALS

click HERE to see where they are on the periodic table
metallic luster...  shiny
high heat and electrical conductivity ... transfers heat and electricity well
malleability .. can pound it into different forms
ductility ... means can pull it out into a thin wire
all metals except mercury SOLID at room temp

NON-METALS

click HERE to see where they are on the periodic table
... not shiny
... insulator, doesnt conduct heat or electricity well
... brittle
... occur as gases,  liquids,  solids

ACID FORMERS  (when put into water)

click HERE to see where they are on the periodic table

ALKALINE FORMERS (when put into water)

click HERE to see where they are on the periodic table
 


click here to see video clip of sodium hitting water at night
click here for a daytime view
THE NOBLE GASES

click HERE to see where they are on the periodic table


 
THE MODERN PERIODIC TABLE
but first, you must click HERE to get a full appreciation of the elements
and HERE is another. I dont know which one I like the best.
Tom Lehrer is an example of the brilliant convergence of science, music and humor.. click HERE

http://chem.lapeer.org/Chem1Docs/Mendeleev.html
1869, Mendeleev, a Russian chemist arranged the elements by atomic mass and properties in his periodic table. His operating principle was that if the elements are arranged in order of increasing atomic weight the "properties" repeated in a regular fashion .. Or a period

The families of elements in his chart have similar properties.  These properties change in a systematic way as we proceed from one element to another within each family.

But the periodic table had gaps.

As a true scientist Mendeleev predicted that there were yet undiscovered elements to be found, and predicted that these elements would have the properties of their groups.  His prediction was correct and elements with those properties were found. http://nobel.scas.bcit.ca/elements/#

THE BASIS OF CHEMICAL REACTIVITY = STABILITY

*** Most elements want to give up or gain electrons to achieve stability

- The changes that elements undergo, like iron rusting, copper getting green, is the element finding stability by combining with an element that WANTS electrons (like oxygen and sulfur).  When they share OR,  give up their electrons they become more stable.
 
It is only the outer electrons that are involved in chemical reactions (remember, giving up or gaining electrons does  not change the element).  The inner electrons are too tightly held to be involved.
THE MAGIC NUMBER IS 8, AN OCTET. If the outer electron shell has 8, the element is happy, happy, happy.  It is stable.

ROW 0 (zero)

Nobel gases with 8 electrons in the outer shell. 

Extremely stable

Most are pretty well known, Neon for lights, Argon for lasers, Krypton for Superman, and Radon because it is radioactive and contaminates the soil, accumulates in our homes and causes lung cancer. 

ROW 1A 

These elements have one electron in their outermost shell.  This makes them VERY unstable and they want to give that electron up to almost anyone which empties the outer shell.  Na11, sodium, as a soft metal is extremely reactive and poisonous. Once it has dumped the electron and become Na+ the ION it is essential for living things. K, potassium is the same and essential for life. They readily form IONIC bonds. 

But the most important element in this group is Hydrogen and this element spends most of its life H+. And it is the basis of fusion in the Sun from which where we get our energy. 

ROW 2A 

These elements have two electrons in their outermost shell. This makes them unstable and they want to give those electrons to almost anyone which empties the outer shell. Mg12 magnesium (Mg2+) and Ca20 calcium (Ca2+), the ions are essential for living things. They readily form IONIC bonds. 

ROW 3A 

These elements NEED more electrons in their outermost shell.  This makes them reactive and they will bond with other elements for stability. They nearly always bond with oxygen to make OXIDES. 
 

ROW 4A

These elements need to share 4 electrons. The basis of all organic molecules is in this group, carbon C6.  This is because carbon can share 4 electrons with 4 different elements and especially because carbon makes long chains of C-C-C-C.  The bonds are covalent and STRONG and for the glue that binds us as well as storage of the energy that sustains us (glucose). 

ROW 5A

Elements in this row like to share 3 covalent bonds with other elements. The important ones are nitrogen N7 essential to proteins and DNA and phosphorus P15 essential to bones and DNA. 

ROW 6A

These elements just need 2 more electrons to be "8" so they like to rip a couple electrons off of other elements and are very reactive, especially oxygen O8.  Oxygen is the most "oxidative" and abundant and readily combines with other elements to make minerals (oxides) as well as water (H2O) in tight covalent bonds.

ROW 7A

These elements are 1 electron shy of the perfect 8. They are explosively reactive and very poisonous.  Fluorine etches metals and glass. Chlorine is essential for life in its ionic form, chloride (Cl-) and part of sodium chloride, AKA table salt, an essential part of the liquid fraction in our blood. They readily form IONIC bonds. 

GIVING UP ELECTRONS - IA and IIA  OR,
ON THE SAD OCCASION OF HAVING ONE OR TWO ELECTRONS IN THE OUTER SHELL.
- starting on the left of the periodic table, the two left columns all have 1 or two electrons in outer shell and want to get rid of them, explosively so.  Hydrogen is explosive, pure sodium reacts violently. Having one or two electrons in the outer shell is NOT energetically stable
- When the number of electrons and # of protons is the same, the net charge is zero.
- when an electron is given up, the net charge becomes +, and the element becomes stable
- in the next row over, the elements will give up 2 electrons, and become 2+
- atoms that have lost or gained an electron become charged and are called IONS

GETTING ELECTRONS - VI and VII OR,
ON THE SAD OCCASION OF BEING SHORT ONE OR TWO ELECTRONS IN THE OUTER SHELL.
- on the far right, chlorine, fluorine which are 1 electron short of a complete octet on the outer shell.  Stability, happiness for chemicals is getting another electron to make 4 pair or 8 in the outer shell
- next row elements, like oxygen want 2 electrons.  In fact, oxygen is a very caustic element that is harsh on other elements, readily reacting with them to rip off their electrons
when oxygen gets 2 electrons, it becomes an ION, O= and usually promptly reacts with the element it took the electrons from, like CO2

IONS
- is a generic name for charged atoms
- typically react with each other oppositely charged ions to form "salts", which is actually a generic term for these kind of compounds
- salts form where an electron is actually given up or obtained, rather than just shared.
- salts form stable combinations so that the net charge is zero, so 1 calcium and 2 chloride ions, but 1 calcium and 1 oxygen
they form IONIC BONDS

REVIEW QUESTIONS

What part of the atom is involved in chemical reactions?
What is the Periodic Table?
Why do atoms give up or get electrons?
What are ions?
How do ions neutralize their charge?
What are the NOBLE GASES
Describe or make a table showing the characteristics of metals and non-metals.
What happens to the extremely reactive elements when put into water?
If given one of the elements we talked about, be able to describe its reaction.
Which part of the atom forms chemical bonds?
Why do all elements except the noble gases and gold and silver chemically react?
What elements would Na most likely react with?
Why do elements like Na react so violently?
What does "stability" mean?
Why do elements like chlorine (Cl) react so violently?
Why isnt NaCl poisonous when Na and Cl isnt?
What are salts?
What kind of bonds do salts form?
Why is oxygen the "great oxidizer"?
Know the basic reactions of the far right and far left elements, well except the noble gases.