Chapter Two Part One Vocabulary

A comprehensive set of 45 vocabulary flashcards covering key concepts from Chapter Two notes on matter, atoms, bonds, water properties, and pH.

Matter

Anything that occupies space and has mass; includes solids, liquids, and gases.

Solid

A state of matter with a definite shape and volume, where particles are tightly packed.

Liquid

A state of matter with definite volume but no fixed shape; it flows to fill space.

Gas

A state of matter with neither fixed shape nor fixed volume; expands to fill space.

Element

A substance that cannot be broken down into simpler substances; made of atoms (e.g., carbon, oxygen).

Atom

The smallest unit of an element that retains its properties; composed of protons, neutrons, and electrons.

Proton

Positively charged subatomic particle located in the nucleus; determines the atomic number.

Neutron

Electrically neutral subatomic particle in the nucleus; contributes to atomic mass.

Electron

Negatively charged subatomic particle outside the nucleus; involved in bonding.

Atomic number

Number of protons in the nucleus; identifies the element.

Atomic mass

Total mass of an atom; roughly the sum of protons and neutrons; used to identify isotopes.

Isotope

Atoms of the same element with different numbers of neutrons; mass varies.

Periodic table

Organization of elements by periods (rows) and groups (columns) showing relationships.

Period

Horizontal row on the periodic table; elements show increasing atomic numbers.

Group

Column on the periodic table; elements in a group have similar chemical properties.

Electron shell / energy level

Regions around the nucleus where electrons reside; shells have capacity limits.

First shell

Innermost electron shell; holds up to 2 electrons.

Outer shell / valence

Outermost electron shell; determines bonding; typically holds up to 8.

Carbon

Element with 6 protons; tends to form four covalent bonds; essential for life.

Hydrogen

Lightest element with 1 proton and 1 electron; most common isotope has 0 neutrons.

Nitrogen

Element with 7 protons; outer shell can hold 5 electrons, often forms 3 bonds.

Oxygen

Element with 8 protons; outer shell holds 6 electrons, typically forms 2 bonds.

Phosphorus

Element essential to life; forms multiple bonds and is a key component of DNA/RNA.

Sulfur

Element essential in biology; commonly forms multiple bonds in biomolecules.

Calcium

Element important for bones and teeth; a major mineral in the body.

Ionic bond

Bond formed by transferring electrons; results in oppositely charged ions.

Covalent bond

Bond formed by sharing electrons between atoms.

Nonpolar covalent bond

Covalent bond with equal sharing of electrons; no partial charges.

Polar covalent bond

Covalent bond with unequal sharing; creates partial positive and negative regions.

Ion

Atom or molecule with a net electric charge due to loss or gain of electrons.

Salt (sodium chloride)

Ionic compound formed from Na+ and Cl−; dissociates into ions in water.

Hydration / dissociation in water

Water facilitates separation of ions by surrounding them; dissolves ionic compounds.

Electrolyte

Ions in solution that conduct electricity.

pH

Measure of how acidic or basic (alkaline) a solution is on a 0–14 scale.

Acids

Substances that release hydrogen ions (H+) in water; pH < 7.

Bases / alkaline

Substances that release hydroxide ions (OH−) or accept H+; pH > 7.

Neutral (pH 7)

A solution with equal concentration of H+ and OH−; examples include pure water.

Solvent

Substance in which solutes dissolve; water is a common biological solvent.

Hydrogen bond

Weak attraction between a partially positive hydrogen and a negatively charged atom; key in water.

Cohesion

Attraction between like molecules, such as water to water.

Adhesion

Attraction between unlike substances, such as water to a surface.

Surface tension

Tendency of liquid surfaces to resist separation; due to cohesion and adhesion.

Capillary action

Movement of liquid through narrow spaces due to cohesive and adhesive forces.

Density

Mass per unit volume; ice is less dense than liquid water, so ice floats.

Density of water versus ice

Liquid water is denser than ice; ice floats on liquid water.

Vaporization

Phase change from liquid to gas; requires heat energy; sweating cools the body.

High heat capacity of water

Water heats and cools slowly, helping stabilize environments and bodily temperatures.

Isotopes (example carbon-12, carbon-13, carbon-14)

Variants of the same element with different neutron numbers; mass differs.

Formation of carbon-14 in the atmosphere

Carbon-14 is produced when cosmic radiation converts atoms in the upper atmosphere.

Proton number vs element identity

The number of protons uniquely determines the element; changing protons changes the element.

Neutrons vs isotopes

Neutron number can vary between isotopes while protons remain the same.

Protons vs electrons balance in neutral atoms

In a neutral atom, the number of protons equals the number of electrons.

Hydrogen’s first shell capacity

The first shell can hold up to 2 electrons, influencing bonding behavior.

Eight-electron outer shell rule (octet)

Most stable atoms seek eight electrons in the outer shell through bonding.

Electron configuration and bonding tendency of carbon

Carbon typically has four electrons in its outer shell and forms four bonds.

Oxygen outer-shell and bonding tendency

Oxygen has six outer-shell electrons and typically forms two bonds.

Hydration shell

Arrangement of water molecules surrounding dissolved ions.

pH scale description

Scale from 0 to 14; lower numbers are more acidic, higher numbers more basic.

Acid examples

Substances like lemon juice that increase H+ concentration in water.

Base examples

Substances that increase OH− concentration or decrease H+ in water.

Neutral examples

Pure water around pH 7; balanced H+ and OH− concentrations.

Ionic dissolution in water

Water separates ions by breaking ionic bonds, producing free ions.

Covalent sharing versus transfer

Covalent sharing bonds atoms by sharing electrons; ionic bonds transfer electrons.