Periodic Table, Periodic Trends, and Electron Configurations

Vocabulary practice flashcards covering periodic trends, historical development of the periodic table, blocks, valence electrons, ions, and ionization energies based on lecture review.

Atomic Radius

One half the distance between the nuclei of two bonded or adjacent identical atoms.

Periodic Law

The principle stating that the physical and chemical properties of elements are periodic functions of their atomic number (or number of protons).

First International Congress of Chemists (1860)

The meeting held in 1860 where chemists settled on standard atomic masses using Carbon-12 ($^{12}C$) as the basis of comparison.

Cannizzaro (Kenny Zaro)

The Italian scientist who presented a convincing method to measure relative masses of atoms, enabling researchers to discover relationships between atomic mass and elemental properties.

Mendeleev (Mandaliv)

The Russian scientist who published the first periodic table in 1869, arranging elements in order of increasing atomic mass while grouping elements with similar chemical properties together.

Moseley (Mostly)

The British scientist who discovered that elements fit into a better repeating pattern when arranged in increasing order of their atomic numbers (number of protons) rather than their atomic masses.

Ionization

Any process that results in the formation of an ion; specifically, converting a neutral atom or molecule into a cation by removing an electron.

Ionization Energy ($IE$)

The energy required to remove one electron from a neutral atom of an element.

Second Ionization Energy ($IE_2$)

The energy required to remove a second electron from an element after the first electron has already been removed (removing an electron from a $+1$ ion).

Third Ionization Energy ($IE_3$)

The energy required to remove a third electron from an element after the first two electrons have already been removed (removing an electron from a $+2$ ion).

Electron Affinity

The energy taken in or given off when an electron is added to a neutral atom to form an anion.

Exothermic Process (Electron Affinity)

An electron affinity process where energy is released (appearing on the product side) when an electron is gained, represented by a negative energy value.

Endothermic Process (Electron Affinity)

An electron affinity process where energy is absorbed or taken in when an electron is gained, represented by a positive energy value.

Cation

A positively charged ion formed when an atom loses electrons; it is always smaller than the neutral atom from which it was formed due to fewer energy levels and stronger nuclear pull.

Anion

A negatively charged ion formed when an atom gains electrons; it is always larger than the neutral atom from which it was formed due to increased electron-electron repulsion and less nuclear attraction per electron.

Valence Electrons

The electrons located in an atom's outermost (highest) main energy level that are available to be lost, gained, or shared in the formation of chemical compounds.

Electronegativity

A measure of the ability of an atom in a chemical compound to attract electrons from other atoms.

Fluorine (Electronegativity Standard)

The most electronegative element on the periodic table, assigned the highest arbitrary electronegativity value of $4$ ($+4$), to which all other elements are compared.

Alkali Metals

The highly reactive metallic elements in Group 1 of the periodic table having an $ns^1$ outer valence configuration, which readily lose one electron to form $+1$ ions.

Alkaline Earth Metals

The reactive metallic elements in Group 2 of the periodic table with an $ns^2$ valence configuration, which lose two electrons to form $+2$ ions.

Halogens

The highly reactive nonmetals in Group 17 with an $ns^2\,np^5$ outer configuration that need only one electron to attain a noble gas configuration, forming $-1$ ions.

Noble Gases

The Group 18 elements characterized by completely filled outer energy sublevels ($ns^2\,np^6$, or $1s^2$ for helium), giving them high chemical stability and very low reactivity.

Lanthanides

The series of 14 elements in Period 6 corresponding to the filling of the $4f$ orbitals, located at the bottom of the periodic table without assigned group numbers.

Actinides

The series of 14 elements in Period 7 corresponding to the filling of the $5f$ orbitals, located at the bottom of the periodic table without assigned group numbers.

Flame Test

A laboratory qualitative analysis method where metal ions in solution are exposed to a flame, emitting distinctive, identifiable colors of light.

Inner Shell Ionization Jump

A sharp, drastic increase between successive ionization energies that occurs when an electron must be removed from an inner core shell possessing a stable noble gas configuration.