Matter+Links

With Inquiry in Action, you can teach physical science and chemistry concepts using an inquiry-based approach that supports national content standards. http://www.inquiryinaction.org/

http://periodic.lanl.gov/chem.shtml http://periodic.lanl.gov/metal.shtml http://periodic.lanl.gov/images/mendeleev.mov > All macroscopic matter is made out of many tiny particles called atoms. The study of how these atoms interact is called //chemistry//. > The three particles that make up atoms are protons, neutrons, and electrons. Protons and neutrons are heavier than electrons and reside in the "nucleus," which is the center of the atom. Protons have a positive electrical charge, and neutrons have no electrical charge. Electrons are extremely lightweight and are negatively charged.They exist in a cloud that surrounds the atom. The electron cloud has a radius 10,000 times greater than the nucleus. > The nucleus of an atom is made up of protons and neutrons in a cluster. Virtually all the mass of the atom resides in the nucleus. The nucleus is held together by the tight pull of what is known to chemists and physicists as the "strong force." This force between the protons and neutrons overcomes the repulsive electrical force that would, according to the rules of electricity, push the protons apart otherwise. > The electron is the lightweight particle that "orbits" outside of the atomic nucleus. Chemical bonding is essentially the interaction of electrons from one atom with the electrons of another atom. The magnitude of the charge on an electron is equal to the charge on a proton. Electrons surround the atom in pathways called orbitals. The inner orbital's surrounding the atom are spherical but the outer orbital's are much more complicated. > Chemically bonding occurs when two particles can exchange or combine their outer electrons in such a way that is energetically favorable. An energetically favorable state can be seen asanalogous to the way a dropped rock has a natural tendency to fall to the floor. When two atoms are close to each other and their electrons are of the correct type, it is more energetically favorable for them to come together and share electrons (become "bonded") than it is for them to exist as individual, separate atoms. When the bond occurs, the atoms become a compound. Like the rock falling to the floor, they "fall" together naturally.
 * **Atom**
 * **Subatomic Particles**
 * **Nucleus**
 * **Electrons**
 * **Chemical Bonding**

Elements can generally be described as either metals or nonmetals. Metal elements are usually good conductors of both electricity and heat. The dividing line between metals and non-metals is not hard and fast, thus the distinction between "Post-transition metals" and "Metalloids" is represented differently on different versions of the Periodic Table. For example, in some tables, Group 12 is is categorized with the post-transition metals, and in others, aluminum and tin are included characterized as Metalloids or poor metals. In our version of the table, we have chosen the most commonly accepted demarcations between these elements.

Hydrogen is group 1 but exhibits few characteristics of a metal and is often categorized with the nonmetals.

About Dimitri Mendeleev
In 1869, the Russian chemist Dimitri Mendeleev noted that repeating patterns of behavior could be seen in the way elements combined with each other. He recognized that the elemental table was a natural phenomenon and not just a convenient tabulation, and because he considered atomic weights as independent variables, he deduced far-reaching and logical consequences. He included “holes” in his table for as yet undiscovered elements and predicted their properties. He is recognized as the father of the modern periodic table.