Daily Archives: June 9, 2011

The Periodic Table of Elements

The Table of elements was started by Johann Dodereiner, a German chemist. He made the Law of Triads. The Law of Triads is when you add the atomic weight of elements that are similar and will add up to the third. This was the first try to group elements. 

In 1862, Alexandre Beguyer de Chancourtois, a French geologist, published the first table. The table had columns around the circumference of a cylinder.

In 1863, John Newlands, an English chemist, published the table with elements in the order of increasing atomic weight but because he didn’t allow space for new elements it was criticized.  

In 1864, Lothar Meyer published a table that described how the elements were placed. He grouped them by their properties. This was the first time someone tried to group the elements by the properties.

After five years, Dmitri Mendeleev challenged himself to rearrange the Table of Elements. He arranged them by the atomic weight and properties. He left several spaces for new elements.

Later on in 1913, Henry Moseley used the X-ray and found that the wavelength of X-radiation of the element decreased with increasing atomic weight, because of the he assigned a new set of numbers to the elements. The new set of numbers is called atomic number. The atomic number is the number of protons or positive charges, contained in the atomic nucleus. There are also electrons which are the negative charge, it is the neutral atom. To find the number of electrons you have to take the atomic weight and subtract it from the atomic number. Now there are many different types of periodic tables such as the cylinder, spiral and much more!

The Periodic Table- powerpoint

Just a little writing project I had to do at school.

Poem-6: My dad is the………………………….

My dad is a robot

He is good at a lot of things.

But you have to tell him what to do.

My dad the math magician.

Ask him any question he will answer it.

What is the square root of 2?  1.414

My dad the turtle.

He is slow and always late.

You want him at 7:30, he comes at 7:50!

My dad the quiet one.

He never yells.

Unless he is very mad.

My dad the helping hand.

He is always their when you need help.

By: Faith Zeng