CHEM114: Valency, Oxidation Numbers, and Chemical Bonds

Vocabulary flashcards based on General Chemistry 1 Week 4 lecture slides covering valency, octet rule, ions, ionic and covalent bonding, properties of chemical compounds, and oxidation states.

Valency

The combining capacity of an atom, or the number of electrons an atom must lose, gain, or share to attain the electronic configuration of the nearest noble gas and form bonds in a compound.

Valence Electrons

The outer-shell electrons of an atom that participate in chemical bonding (for elements with an atomic number of $30$ or less).

Octet Rule

A chemical principle formulated in 1916 by Gilbert N. Lewis stating that atoms tend to react to achieve the most stable state possible by having eight electrons in their valence shell.

Ion

A charged particle formed when electrons are removed from or added to an atom, while the nucleus remains unchanged by the chemical process.

Cation

A positively charged ion formed when an atom loses electrons; typically formed by elements positioned on the left side of the periodic table.

Anion

A negatively charged ion formed when an atom gains electrons; typically formed by elements positioned on the right side of the periodic table.

Ionic Bond (Electrovalent Bond)

A chemical bond formed when a complete transfer of electrons occurs between atoms, wherein one element loses electrons and another gains them, yielding oppositely charged ions.

Covalent Bond

A chemical bond formed when atoms unite by sharing electrons from their outermost shells.

Ionic Compounds

Compounds characterized by strong electrostatic attractive forces, high melting and boiling points, electrical conductivity in molten or aqueous states, and solubility in water rather than organic solvents.

Covalent Compounds

Compounds held by weak intermolecular forces of attraction, characterized by low melting and boiling points, electrical non-conductivity, and solubility in organic solvents rather than water.

Oxidation Number (Oxidation State)

The charge assigned to an atom in a particular molecule or ion, representing the total number of electrons gained or lost to form a chemical bond with another atom.

Peroxides

Compounds containing the $O_2^{2-}$ ion, in which each oxygen atom possesses an exceptional oxidation number of $-1$ instead of the usual $-2$.

Electronegativity

A measure of an atom's tendency to attract electrons towards itself; in covalent bonds, the more electronegative atom is assigned the negative oxidation state.

Ternary Compound

A compound composed of three different elements combined in a fixed proportion by mass (e.g., $KMnO_4$).

Polyatomic Ion

An ion composed of two or more covalently bonded atoms carrying a net overall electrical charge, with the sum of its oxidation numbers equaling the ion's charge.

"bi-" (Nomenclature Prefix)

A chemical prefix used interchangeably with "hydrogen" when naming hydrogenated oxyanions (e.g., bicarbonate for hydrogen carbonate or bisulfate for hydrogen sulfate).