Periodic Table Trends

The periodic table is a carefully organized table, with elements categorized by their similar properties. Trends help us understand the periodic table better, because you are able to see the pattern in the rows and columns of the periodic table!

There are different properties to view trends. For example:

• Melting and boiling point

• Ionization energy

• Electronegativity

• Atomic radius

                                                             Melting and boiling point

The trend is:

-boiling/melting point increases from left to right

-Boiling/melting point decreases going from up to down

-the elements in the centre of the table have the highest boiling and melting point (hence the red colour in the middle!)
-noble gases have the lowest boiling/melting point

 

Ionization Energy

The trend is:

-ionization increases going left to right

-ionization decreases going down

-noble gases have high ionization energy   

Electronegativity

The trend is:

-electronegativity increases going from left to right

-electronegativity decreases going up to down

As you can see, the trends prove to us that the elements on the periodic table have been placed there for a specific reason!

Want to learn more?

http://www.youtube.com/watch?v=h7XWqwgZII0

http://www.youtube.com/watch?v=CHHy2ex0dw4

A Roller Coaster Ride through Electron Configuration

*looks different depending on orbital

Structure of the Atom

An atom is composed of 3 subatomic particles: proton, neutron, electron!

Protons have a positive charge, usually represented by the symbol: P

Neutrons have a neutral charge, usually written in the form of N

Both of these subatomic particles are found in the nucleus. However, the electrons are found orbiting around the nucleus. This subatomic particle has a negative charge.

On the periodic table, the number of protons in the nucleus can found by looking at the atomic number (which is located right above the atomic symbol).
Right below the atomic symbol is the atomic mass, which is the total number of the neutron and the proton. To get the number of the neutron in the atom, simply subtract the atomic number from the atomic mass!













Isotopes:

Isotopes are atoms that have the same atomic number, but a different number of neutron! This results in the atom having a different weight!

Important People who Contributed to Our Understanding of the Atom

The History of the Periodic Table

The history of the periodic table dates back all the way to the 1800's. It was a long progress for it to become what it is today; going through studies of many famous scientists of those days, changing format, changing patterns and theories. In 1863, 52- 62 elements were discovered and even before then the first attempt in trying to organize those elements was done by William Odling, but didn’t succeed. Three years later, mister John Newlands thought he had found a pattern, where every 8th element shared common properties. It was given a name as well, calling it the “law of octaves”, but it wasn’t consistent as he kept changing it therefore didn’t work. Another three years later it was time for Dimitri Mendeleev’s turn to ponder over the table of elements and was successful! He found a method where it shows the elements masses and properties. He was the one that gave the name “periodic table” as he arranged the elements in periods (rows) and in groups (columns), also that the elements recur periodically, a suitable name. Mendeleev thought it out carefully; leaving gaps just in case new elements were to be discovered, allowing predictions of the properties & characteristics and understanding to the data.

                The modern Periodic table today is organized according to atomic number than of the atomic mass. We learn from the periodic table by knowing the Periodic law: properties of the chemical element recur periodically when the elements are arranged from the lowest to highest atomic number. There are different sections of the table that you should know by now: Alkali Metals, Alkali Earth Metals, Transition Metals, Halogens, noble gases and the “inner-transition metals” there are lanthanides (first row underneath the table) and actinides (underneath lanthanides).