Atomic Structure and Chemical Bond

A comprehensive set of vocabulary flashcards covering atomic structure, subatomic particles, quantum levels (shells, subshells, orbitals), and chemical bonding (ionic and covalent) based on the lecture transcript.

Element

A simplest pure substance that cannot be split into or built up from other simpler substances by any chemical reaction.

Robert Boyle

The scientist who first used the term element in $1661\text{ AD}$.

Molecule

A group of two or more atoms tightly held together by chemical bonds; the smallest particle of an element or compound that exists independently.

Atom

The smallest particle of an element that takes part in a chemical reaction without being divided.

Subatomic Particles

The smaller particles contained within atoms, primarily consisting of electrons, protons, and neutrons.

Electron $(e)$

A negatively charged subatomic particle found in shells, with a relative mass of $1/1837\text{ amu}$ and an absolute mass of $9.109 \times 10^{-22}\text{ g}$.

Proton $(p^+)$

A positively charged subatomic particle located in the nucleus with a relative mass of $1\text{ amu}$ and an absolute mass of $1.67 \times 10^{-24}\text{ g}$.

Neutron $(n^0)$

A neutral subatomic particle located in the nucleus with a relative mass of $1\text{ amu}$ and an absolute mass of $1.67 \times 10^{-24}\text{ g}$.

Niels Bohr

The Danish physicist who in $1913$ proposed an atomic model where electrons revolve around a positively charged nucleus in definite orbits or shells.

Ground State

The stable state of an atom where electrons revolve in their lowest energy discrete orbits without losing energy.

Duplet Rule

The tendency of certain elements like hydrogen, lithium, and beryllium to achieve a stable electronic configuration similar to helium by having two electrons in their outermost K-shell.

Octet Rule

The rule stating that atoms of the first $20$ elements combine to have eight electrons in their outermost shell to achieve stability similar to inert gases.

Valence Shell

The outermost shell of an atom which holds the electrons primarily responsible for chemical reactions.

Valence Electrons

The electrons present in the outermost shell of an atom that can be gained, lost, or shared during chemical reactions.

Core

The part of an atom excluding the valence shell, which includes core electrons, protons, and neutrons.

Shells (Energy Levels)

Specific paths around the nucleus designated by numbers $n = 1, 2, 3, 4, 5, 6, 7$ or letters $K, L, M, N, O, P, Q$.

Subshells

Finer divisions within shells designated by letters $s, p, d, \text{ and } f$, derived from spectral patterns sharp, principal, diffuse, and fundamental.

Orbitals

Specific regions within subshells where the probability of finding an electron is approximately $95\text{\%}$; each can hold a maximum of $2$ electrons.

Electronic Configuration

The systematic representation of the distribution of electrons in the different shells or orbitals of an atom.

Aufbau Principle

The principle stating that electrons fill orbitals of lower energy levels first; for example, the $4s$ orbital is filled before the $3d$ orbital.

Valency

The combining capacity of an atom, defined as the number of electrons it loses, gains, or shares to achieve an octet in its valence shell.

Variable Valency

A phenomenon where elements, particularly transition elements in groups $3\text{-}12$, exhibit more than one valency due to partially filled $d\text{-orbitals}$.

Ions

Charged particles formed when atoms lose or gain electrons to achieve electrical stability.

Cations

Positively charged ions formed when atoms with $1, 2, \text{ or } 3$ valence electrons lose those electrons.

Anions

Negatively charged ions formed when atoms with $5, 6, \text{ or } 7$ valence electrons gain electrons to complete their octet.

Electrovalent Bond (Ionic Bond)

A chemical bond formed by the transfer of electrons from the valence shell of a metal atom to the valence shell of a non-metal atom.

Electrovalency

The number of electrons an atom loses or gains during the formation of an ionic bond to attain a stable electronic configuration.

Covalent Bond

A chemical bond formed by the mutual sharing of an equal number of electrons between two atoms.

Covalency

The number of electrons an atom shares to form a covalent bond.