In 1869, Dmitri Mendeleev published the periodic table. This table is a visual creation of the periodic law. It states the certain properties of elements, arranged by the atomic number. They arranges elements into vertical columns which are also know as groups and horizontal rows which are know as periods.
Here is a worksheet that we did on the periodic tables. We found the elements with the highest and lowest boiling point, melting point, density, atomic radius, electronegatvity and the number of isotopes in each different row.
Amedeo Avogadro was born August 9,1776 in Turin, Italy. He was born to a family of lawyers. He followed his family's footsteps and graduated in ecclesiastical law at age 20 and began to practice law. But he was also interested in the natural sciences and in 1800 he began private studies in physics and mathematic. In 1809, he started teaching the natural sciences in a liceo in Vericelli. It was in Vericelli that Avogadro wrote a memoir in which he declared the hypothesis that is now known as Avogadro's law. In 1820, Avogadro became the first chair of mathematical physics at Turin University. He had six children and was reputed to be a religious man and also a discreet lady's man. He died July 9,1856.
Avogadro's law states that equal volumes of gases, at the same temperature and pressure, contain the same number of molecules. One of the most important contributions of Avogadro's work was his resolution of the confusion surrounding atoms and molecules. Avogadro believed that particles could be composed of molecules and that molecules could be composed of still simple units, atoms. The number of molecules in a mole was termed Avogadro's number in honor of Avogadro's theories. Avogadro's number has been experimentally determined to be 6.o23x10^23 molecules per gram-mole. Here is our mole that we have done for this day.
What is an atom? Atoms are the basic unit of chemical element.
They are the basic building blocks of ordinary matter.
Atoms are composed of particles called protons, electrons, and neutrons.
The protons carry a positive electrical charge, the electrons carry out
a negative electrical charge, and the neutrons carry no electrical
charge. Protons are the atomic number. Protons and Neutrons make up the
mass number ( PROTON + NEUTRON = MASS NUMBER.) The Electrons equal the
same number as the protons.
The element symbol is abbreviation from the elements name. In the picture below it shows the atomic number on top and the Atomic mass number on the bottom. On others it would have the name of the element between the element symbol and the atomic mass.
Isotopes
An isotope has a different number of neutrons an a atom. Which means the atomic mass number will change but the proton number will not changes. For example in the picture below it shows carbon having three different atomic mass numbers, which means it is an isotope.