Chemical Stability, Octet Rule, and Physiological Ions

Vocabulary flashcards covering chemical stability, octet rule, ion formation (cations and anions), and common physiological ions in the human body.

Octet Rule

The tendency of elements to lose, gain, or share electrons in order to obtain complete outer shells with eight electrons.

Noble Gases

Elements located in column VIIIA that have a complete outer shell, making them stable and unreactive.

Ion

A charged structure produced from the loss or gain of electrons by an atom.

Cation

A positively charged ion formed when an atom loses electrons (examples include $\text{Na}^+$, $\text{K}^+$, and $\text{Ca}^{2+}$).

Anion

A negatively charged ion formed when an atom gains electrons (examples include $\text{HCO}_3^-$ and $\text{Cl}^-$).

Sodium Ion Formation

Sodium reaches stability by donating an electron to satisfy the octet rule, leaving it with 11 protons, 10 electrons, and a $+1$ charge ($\text{Na}^+$).

Chlorine Ion Formation

Chlorine reaches stability by gaining an electron to satisfy the octet rule, leaving it with 17 protons, 18 electrons, and a $-1$ charge ($\text{Cl}^-$).

Sodium Ion ($\text{Na}^+$)

The most common extracellular cation; functions in propagating electrical signals in nerves and muscle, osmotic movement of water, and cotransport of substances across plasma membranes.

Potassium Ion ($\text{K}^+$)

The most common intracellular cation; plays a role in propagating electrical signals in nerves and muscle, glycogen storage in liver and muscle, and pH balance.

Calcium Ion ($\text{Ca}^{2+}$)

A cation that hardens bone and teeth, and participates in muscle contraction, exocytosis (including release of neurotransmitter), blood clotting, and acting as a second messenger in hormonal stimulation of cells.

Magnesium Ion ($\text{Mg}^{2+}$)

A common cation in the human body required for ATP production.

Hydrogen Ion ($\text{H}^+$)

A cation whose concentration determines the pH of blood and other body fluids.