Periodic table and Periodic trends

Mendeleev

The originator of the periodic table was russian chemist Dmitri Mendeleev (1834-1907). He originally ordered the periodic table by increasing atomic mass, with elements having common properties under each other.

Period

A horizontal row of elements in the periodic table.

Anion

A negatively charged ion. Anions have more electrons than the atom it is made from, so there will be more repulsion between them, causing increase in radius

Cation

A positively charged ion. Cations have less electrons, so they will have one less energy level than the element made from.

Group

A vertical row of elements on the periodic table.

Representative Elements

All of the elements found in the s-orbital and p-orbital areas are called the representative elements.

Ion

An atom that loses or gains electrons to have a full outside energy level. In doing so, it becomes charged--ceasing to be electrically neutral.

Transition metal

An element in groups 3-12 that is contained in the d-block of the Periodic Table and, with some exceptions, is characterized by a filled outermost s orbital of energy level n, and filled or partially filled d orbitals of energy level n-1

Chalcogens

Another name for the oxygen group.

Atomic Radius

Atomic size increases down a group. Atomic size decreases from left to right across a period The increasing trend occurs because as you go down a group more energy levels cause the atom to be larger. Shielding also affects the size; the electrons in lower energy levels cause less pull to those electrons outside of it.

Carbon, Nitrogen,Oxygen Families

Because of the fact that they are bisected by the metal/ nonmetal line and don't have as many similar properties, they are more of a loose grouping.The oxygen group also carries the name chalcogens.

Ion Size

Essentially the same trend as atomic size, except anions are always bigger than cations.

Halogens

Group 17; contains nonmetals; 7 electrons in its outermost energy level; very reactive; poor conductors of electric current; never in its uncombined form in nature; combine with most metals to form salts.

Alkali Metals

Group 1A is called the Alkali Metals. These are the most reactive elements on the periodic table.

Henry Mosley

He had the idea to order the table based on the atomic number, instead of the mass, giving us a table much like the one we now have today.

Actinides

In the 2nd row of transition metals, radioactive, unstable, do not occur in nature, most are artificial

Inner Transition Metals

Inside the inner transition metal group, there are two categories:The Lanthanide Series, which is the top row in the inner transition metal, and the actinide series which is the second row.

1st Ionization Energy

Ionization energy increases up a group. Ionization energy increases left to right across a period

Alkaline Earth Metals

Next to the alkali metals come the alkaline earth metals.

Noble Gases

One of the elements of group 18 of the periodic table (helium, neon, argon, krypton, xenon, and radon); noble gases are unreactive. This is because they have a completely full outside energy level, making them more stable than other elements.

Other Metals

Other metals include transition metals, inner transition metals (a.k.a. rare earth metals) and other metals.

Oxidation Number

Oxidation number is the charge that an element has after it becomes an ion.

Metal/Nonmetal Line

Separates metals from non-metals on the periodic table.

Ionization energy

The amount of energy it takes to pull an electron from the outside shell of an atom. 1st Ionization energy is the amount of energy to pull the first electron away, the 2nd ionization energy is the amount of energy to pull away a second electron, etc.

Lanthanides

The first of the two rows below the main part of periodic table. usually used in alloys, soft, malleable, shiny and good electrical conductors

2nd Ionization Energy

The second ionization energy follows the same general trend as the first, except that all the elements in the first group have the highest IE. This is because after the first row loses one electron it has a full valence, making as stable as possible. It takes much more energy to take away a second electron.

Electronegativity

The tendency for the atoms of the element to attract an electron when combining with other elements. Electronegativity increases up a group. Electronegativity increases from left to right across a period. The exception to the general trend for electronegativity is that the noble gases have a value of zero!

Valence Electrons

Valence electrons increase from left to right across a period. Valence electrons are the same in a group.

Periodic Law

When the elements are arranged in order of atomic number, there is a periodic repetition of their chemical and physical properties.

Nonmetals

generally non-lustrous and are poor conductors of electricity. Ex: Helium and other gases are nonmetals.

Metals

have a high electrical conductivity and a high luster when clean. They are ductile and malleable.

Metalloids

show properties of both metals and nonmetals—they are on both sides of the metal/nonmetal line