Unit 3: Periodic Table of Elements Flashcards

Vocabulary flashcards covering the history, classification, organization, periodic trends, bonding, and valency of chemical elements based on the lecture transcript.

Element (Boyle's Definition)

Defined in $1661$ by Robert Boyle as a substance that cannot be broken down into a simpler substance by a chemical reaction.

Ununennium

Also known as eka-francium or element $119$ (symbol $Uue$), a hypothetical s-block alkali metal with atomic number $119$ expected to be the first element in the eighth period.

Triads

A classification introduced by Johann Wolfgang Döbereiner in $1829$ grouping three elements with similar traits by atomic mass, where the atomic weight of the middle element was roughly the average of the other two.

Law of Octaves

Proposed by John Newlands in $1864$, an arrangement of elements by increasing atomic weight where every eighth element shared similar properties.

Modern Periodic Law

Established following Henry Moseley's $1913$ discovery, stating that properties of elements change periodically based on their atomic number, not their atomic weight.

Noble Gases

Colorless, monatomic gases in Group VIII-A or Group O with atomic numbers $2$, $10$, $18$, $36$, $54$, and $86$ that are chemically un-reactive, diamagnetic, and possess stable electron configurations.

Representative Elements

Also called main-group elements, these are found in the A-Families (Groups $1$, $2$, and $13$ through $18$) in the s-block and p-block, whose outer shell contains their valence electrons.

Diamagnetic Elements

Elements that are repelled by a magnetic field because all of their electrons are paired.

Paramagnetic Elements

Elements that are drawn into a magnetic field because they contain unpaired electrons.

Transition Elements

Metals in the B-Families (Groups $3$ to $12$) sitting in the d-block with partly filled d-orbitals, characterized by high melting points, paramagnetic properties, and colored compounds.

Inner Transition Elements

Paramagnetic metallic f-block elements found at the bottom of the periodic table belonging to the $6\text{th}$ and $7\text{th}$ periods after Group III-B, divided into Lanthanoids and Actinoids.

Lanthanoids

Also known as rare earth elements, a series of elements with atomic numbers $57$ through $71$ (specifically cerium through lutetium) named after Lanthanum.

Actinide Series

A series of $14$ radioactive elements with atomic numbers $89$ through $102$.

Transuranium Elements

Elements in the periodic table with atomic numbers of $93$ and above.

Period

The collective name for all elements arranged in a single horizontal row in the periodic table, representing energy levels or electron shells.

Group (or Family)

The collective name for elements that appear in one of the $18$ vertical columns in the periodic table, sharing the same number of outer electrons and similar properties.

Metals

Elements making up about $80\%$ of the periodic table that are good conductors of heat and electricity, shiny, malleable, ductile, and mostly solid at room temperature except mercury.

Nonmetals

Elements located on the upper right side that are poor conductors of heat and electricity, dull, brittle as solids, and exist as solids, gases, or liquid bromine.

Metalloids

Elements located along the staircase line that exhibit properties of both metals and non-metals and act as semiconductors.

Atomic Radius

One-half the distance between the nuclei of identical atoms joined in a molecule, representing total distance from nucleus to outermost electron orbital.

Ionization Energy

The minimum energy required to remove an electron from a gaseous atom or ion in its ground state.

Electron Affinity

The energy change that occurs when an electron is added to a neutral gaseous atom, where a more negative value indicates a higher affinity.

Cation

A positively charged ion formed when an atom loses one or more negative electrons.

Anion

A negatively charged ion formed when an atom gains one or more negative electrons.

Molecule

A neutral group of two or more atoms chemically bonded together through covalent bonding, representing the smallest unit of a chemical compound retaining its chemical properties.

Ionic Compounds

Compounds held together by electrical attraction (ionic or electrovalent bonds) between cations and anions formed by electron transfer between a metal and a non-metal, forming a $3\text{D}$ crystal lattice.

Covalent Compounds

Also called molecular compounds, these form when two or more non-metal atoms share electrons via covalent bonding and exist as distinct individual molecules.

Valency

A number serving as a measure of the combining capacity of an element when forming compounds, equal to ionic charge in ionic compounds or bond count in covalent compounds.