Periodic Table Organization and Periodic Properties

Flashcards covering the history of the periodic table, classifications of elements (metals, nonmetals, metalloids, groups, and periods), and key periodic trends including atomic radius, ionic radius, ionization energy, electronegativity, and metallic character.

Dmitri Mendeleev

The scientist who in 1869 arranged the 60 known elements in order of increasing atomic mass, observed a periodicity of properties, and predicted the properties of undiscovered elements by identifying gaps in the table.

Henry Moseley

The scientist who determined in 1913 that the physical and chemical properties of elements are periodic with respect to nuclear charge (atomic number) rather than atomic mass.

Modern Periodic Law

The law stating that the physical and chemical properties of the elements are periodic functions of their atomic numbers (nuclear charges).

Group (Family)

Each vertical column on the periodic table, indicated by a group number at the top, whose elements share similar chemical and physical properties.

Period

A horizontal row in the periodic table; lanthanides and actinides are considered part of Periods 6 and 7, respectively.

Alkali Metals

The elements in Group 1A (excluding hydrogen), characterized as highly reactive metals.

Alkaline Earth Metals

The metallic elements in Group 2A that are shiny like alkali metals, but are less reactive.

Halogens

The elements in Group 7A (such as fluorine and chlorine) that are highly reactive nonmetals.

Noble Gases

The elements in Group 8A that are unreactive and do not readily form chemical compounds.

Transition Elements

The metallic elements situated in the middle of the periodic table in Groups 3 through 12.

Representative Elements

The main group elements located in Groups 1, 2, and 13 through 18 (Groups 1A through 8A) of the periodic table.

Inner Transition Metals

The two extra rows positioned at the bottom of the periodic table, comprising the lanthanides and actinides.

Lanthanides

The top row of the inner transition metals, belonging to Period 6 and also known as rare earth elements.

Actinides

The bottom row of the inner transition metals, belonging to Period 7 of the periodic table.

Metals

Elements situated to the left of the periodic table's zigzag line that are shiny, ductile, malleable, good conductors of heat and electricity, have higher melting points, and are solid at room temperature except mercury ($Hg$), which is a liquid.

Ductility

The mechanical property of a material, characteristic of metals, enabling it to be pulled or shaped into thin wires.

Malleability

The physical property of a metal that allows it to be hammered, rolled, or shaped without breaking.

Nonmetals

Elements situated to the right of the periodic table's zigzag line that are not shiny, not ductile, brittle, poor conductors of heat and electricity (insulators), and have low melting points and low density.

Metalloids (Semi-metals)

Elements along the zigzag dividing line that exhibit properties of both metals and nonmetals, and can function as semiconductors.

Semiconductor

A material, characteristic of metalloids, that can be configured to function either as an electrical conductor or an insulator.

Valence Electrons

Electrons located in the highest energy level of an atom, the quantity of which can be determined by identifying an element's column/group number.

Atomic Radius Trend

The trend in atomic size that increases from top to bottom down a group as valence electrons occupy higher energy levels, and decreases from left to right across a period as an increasing number of protons pulls electrons closer.

Atomic Radius vs. Atomic Number Graph

A plot of atomic radius as a periodic function of atomic number, exhibiting sharp periodic peaks at Group 1 alkali metals ($Li$, $Na$, $K$, $Rb$, $Cs$, $Fr$) and minima at the end of each period.

Cation

A positively charged ion formed when a neutral atom loses one or more electrons; it always has a smaller radius than its neutral parent atom.

Anion

A negatively charged ion formed when a neutral atom gains one or more electrons; it always has a larger radius than its neutral parent atom.

Atomic vs. Ionic Radii Comparison

Graphs demonstrating that cations ($Li^+$, $Na^+$, $K^+$, $Rb^+$, $Cs^+$) are smaller than their corresponding neutral atoms, whereas anions ($F^-$, $Cl^-$, $Br^-$, $I^-$) are larger than their corresponding neutral atoms.

Ionic Radius Periodic Trend

top to bottom - increases same reason as atomic radius

left to right - fluctuates, starts small, smaller, very large, then smaller, when it is a metal it loses electorns, then metalloids and non metals gain. it wants to be 8 valence electrons.

Ionization Energy

The energy required to remove an electron from an atom in the gas phase; removing the first electron forms a cation with a charge of $+1$.

Ionization Energy Group Trend

First ionization energy decreases going from top to bottom down a group because valence electrons are farther from the nucleus, decreasing the energy required to pull them off.

Ionization Energy Period Trend

First ionization energy increases going from left to right across a period because the increasing number of protons pulls electrons closer to the nucleus, requiring more energy to remove them.

Ionization Energy Orbital Pairing 'Blips'

Small decreases in the ionization energy trend across a period (such as from nitrogen to oxygen, or phosphorus to sulfur) that occur because removing an electron from a doubly occupied orbital requires less energy due to electron-electron repulsion.

Electronegativity

A measure of how strongly an atom attracts electrons toward itself in a chemical bond; it decreases from top to bottom down a group and increases from left to right across a period.

Metallic Character

The characteristic of an element describing how easily it loses valence electrons; it is most prevalent on the left side of the periodic table (metals) and decreases moving from left to right.