lab #2 Chemical Bonds, Water, and pH

30 vocabulary flashcards summarizing key terms about ionic, covalent, and hydrogen bonding, molecular polarity, water properties, and pH concepts from Lab 2 notes.

Valence Shell

The outermost electron shell of an atom; atoms are most stable when this shell is full.

Valence Electrons

Electrons located in the valence shell that participate in chemical bonding.

Chemical Bond

An attraction between atoms formed to fill valence shells, producing more-stable arrangements.

Molecule

A chemical structure made when two or more atoms bond together (e.g., H₂O).

Ion

An atom or group of atoms with a net electric charge resulting from electron loss or gain.

Cation

A positively charged ion produced when an atom donates one or more electrons.

Anion

A negatively charged ion produced when an atom accepts one or more electrons.

Ionic Bond

An electrostatic attraction between oppositely charged ions created by electron transfer; common in crystalline solids like NaCl.

Opposite Charges Attract

Basic electrostatic rule explaining why cations and anions stay together in ionic compounds.

Covalent Bond

A strong bond formed when two atoms share one or more pairs of electrons.

Single Covalent Bond

A bond in which one pair (two) of electrons is shared; represented by one solid line.

Double Covalent Bond

A bond in which two pairs (four) of electrons are shared; represented by two lines.

Triple Covalent Bond

A bond in which three pairs (six) of electrons are shared; represented by three lines.

Polar Covalent Bond

A covalent bond with unequal electron sharing, producing partial charges (δ+ and δ-).

Nonpolar Covalent Bond

A covalent bond with equal electron sharing, resulting in no partial charges.

Polar Molecule

A molecule whose shape and bond polarity create distinct positive and negative ends (e.g., water).

Nonpolar Molecule

A molecule with even charge distribution; may contain nonpolar bonds or symmetry that cancels polarities (e.g., methane, CO₂).

Hydrogen Bond

A weak attraction between a δ+ hydrogen in one polar bond and a δ- atom (O, N, Cl) in another molecule or region.

Surface Tension

The cohesive ‘skin’ on liquid water produced by the collective strength of many hydrogen bonds.

Water (H₂O)

A polar molecule with two O–H polar bonds and a bent geometry; forms extensive hydrogen bonding.

Methane (CH₄)

A nonpolar molecule whose four C–H bonds are nonpolar and arranged tetrahedrally.

Carbon Dioxide (CO₂)

A linear molecule with polar C=O bonds that cancel, making the overall molecule nonpolar.

pH

A logarithmic measure of hydrogen ion (H⁺) concentration ranging from 0–14; 7 is neutral.

Hydrogen Ion (H⁺)

A proton released into solution; its concentration determines acidity.

Hydroxide Ion (OH⁻)

A negatively charged ion whose presence or production increases basicity.

Acid

A substance that adds H⁺ to a solution; pH < 7 indicates acidity.

Base

A substance that adds OH⁻ or removes H⁺ from a solution; pH > 7 indicates basicity.

Strong Acid

An acid far below pH 7 with a very high H⁺ concentration compared to OH⁻.

Strong Base

A base far above pH 7 with a very high OH⁻ concentration compared to H⁺.

Logarithmic Scale (pH)

Each whole pH unit represents a ten-fold change in H⁺ concentration, making the scale logarithmic.