Bonding, Molecules, & Compounds

What is the Octet Rule?

Atoms tend to gain, lose, or share electrons to achieve a full valence shell of 8 electrons, similar to noble gases.

What is an ion?

A charged atom or molecule due to the loss or gain of electrons.

What are cations

Positively charged ion (loses electrons).

What are anions

Negatively charged ion (gains electrons).

Name 3 essential cations in the body and their functions.

• Na⁺ (Sodium): Nerve signaling, fluid balance

• K⁺ (Potassium): Muscle contraction, heart function

• Ca²⁺ (Calcium): Bone health, muscle contraction

Name 3 essential anions in the body and their functions.

• Cl⁻ (Chloride): Maintains fluid balance

• HCO₃⁻ (Bicarbonate): Maintains pH balance

• PO₄³⁻ (Phosphate): DNA & ATP structure

What is an ionic bond?

A bond formed by the transfer of electrons from one atom to another, creating oppositely charged ions.

What is a covalent bond?

A bond formed by the sharing of electrons between two nonmetals.

example of an ionic compound

NaCl (Sodium Chloride)

example of covalent compound

H₂O (Water)

What is a polyatomic ion?

A charged group of covalently bonded atoms that act as a single ion.

Name 3 common polyatomic ions and their formulas.

• Ammonium (NH₄⁺)

• Nitrate (NO₃⁻)

• Sulfate (SO₄²⁻)

What is electronegativity?

An atom’s ability to attract electrons in a bond.

How does electronegativity determine bond type?

• Nonpolar Covalent: Electrons shared equally (small difference in electronegativity).

• Polar Covalent: Electrons shared unequally (moderate difference).

• Ionic: Electron transfer (large difference).

  (The bigger the difference, the more unequal the sharing of electrons.)

Which element has the highest electronegativity?

Fluorine (F)

Which ion is essential for nerve signaling?

K⁺

Phosphate (PO₄³⁻) is important in:

DNA structure and ATP production

Do anions gain or lose electrons?

Anions gain electrons.

Are anions usually metals or nonmetals?

Nonmetals.

How do you recognize a cation?

It has a positive sign (like Na⁺, Ca²⁺).

Do cations gain or lose electrons?

Cations lose electrons.

Are cations usually metals or nonmetals?

Metals.