S.3–S.4 Vocabulary Review: Basic Atomic Structure to Scientific Method

Vocabulary flashcards covering basic atomic structure, matter, chemical bonds, reactions, solutions, osmosis/diffusion, acids/bases, and scientific method concepts.

Atom

The smallest unit of an element that retains its properties; composed of a nucleus and surrounding electrons.

Nucleus

The center of the atom that contains protons and neutrons.

Proton

Positively charged subatomic particle in the nucleus.

Neutron

Electrically neutral subatomic particle in the nucleus.

Electron

Negatively charged subatomic particle surrounding the nucleus; very small and involved in bonding.

Isotope

Atoms of the same element with different numbers of neutrons.

Atomic number

Number of protons in the nucleus; defines the identity of the element.

Mass number

Total number of protons and neutrons in the nucleus.

Atomic mass

Approximately the mass of the atom, determined by protons and neutrons.

Ion

An atom with a net electric charge due to gain or loss of electrons.

Cation

Positively charged ion (more protons than electrons).

Anion

Negatively charged ion (more electrons than protons).

Valence electrons

Electrons in the outermost shell that determine bonding behavior.

Orbital

Region around the nucleus where electrons reside; named by sublevels (s, p, d, f).

Group

Vertical column in the periodic table; elements with similar valence configurations.

Period

Horizontal row in the periodic table; indicates outer shell occupation.

Metals

Elements that tend to lose electrons; good conductors and shiny.

Nonmetals

Elements that tend to gain electrons; varied properties, often poor conductors.

Metalloids

Elements with properties between metals and nonmetals; near the staircase.

Noble gases

Group 18 elements with full valence shells and high chemical stability.

Full valence shell

Outermost electron shell that is complete, giving chemical stability.

Ionic bond

Bond formed by transfer of electrons from a metal to a nonmetal, creating oppositely charged ions.

Covalent bond

Bond formed by sharing electrons between two nonmetals.

Polar covalent bond

Covalent bond with unequal sharing of electrons, creating partial charges.

Nonpolar covalent bond

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

Metallic bond

Bond in metals with delocalized electrons moving between atoms.

Electronegativity

Tendency of an atom to attract bonding electrons.

Ionization energy

Energy required to remove an electron from an atom.

Molar mass

Mass in grams of one mole of a substance; sum of atomic masses.

Mole

Amount of substance containing 6.022 x 10^23 particles.

Avogadro's number

6.022 x 10^23; number of particles in one mole.

Molarity

Moles of solute per liter of solution (mol/L).

Molality

Moles of solute per kilogram of solvent (mol/kg).

Mass percent

Mass of solute per mass of solution × 100.

Saturated solution

Solution containing the maximum amount of solute dissolved at a given temperature.

Unsaturated solution

Less than the maximum amount of solute is dissolved.

Supersaturated

Solution containing more solute than normally dissolves at that temperature.

Solvent

Substance that dissolves the solute.

Solute

Substance that is dissolved in the solvent.

Solution

Homogeneous mixture of solute dissolved in solvent; uniform at the molecular level.

Diffusion

Movement of particles from high concentration to low concentration.

Osmosis

Diffusion of water across a selectively permeable membrane from high to low water potential.

Hydrophilic

Water-loving; substances that interact with water.

Hydrophobic

Water-fearing; substances that repel water.

Isotonic

Solutions with equal solute concentrations; no net osmosis.

Hypertonic

Solution with higher solute concentration than another; can cause cell shrinkage.

Hypotonic

Solution with lower solute concentration; can cause cell swelling or bursting.

pH

Measure of acidity or basicity on a 0–14 scale;

Acids

Substances that donate H+ ions in aqueous solution.

Bases

Substances that increase OH− ions in aqueous solution.

Buffer

Substance that resists changes in pH by neutralizing added acids or bases.

Neutralization reaction

An acid reacts with a base to form a salt and water.

Acid–base chemistry

Study of acids (H+ donors) and bases (OH− donors) and their reactions.

Synthesis (reactions)

Reaction where two or more substances combine to form a single product.

Decomposition

Reaction where a compound breaks down into simpler substances.

Single displacement

Reaction where an element replaces another in a compound.

Double displacement

Reaction where ions in two compounds exchange partners.

Collision theory

Particles must collide with enough energy and correct orientation to react.

Catalyst

Substance that speeds up a reaction without being consumed.

Activation energy

Minimum energy required to start a chemical reaction.

Endothermic

Reactions that absorb heat from the surroundings.

Exothermic

Reactions that release heat to the surroundings.

Chemical equilibrium

State in which forward and reverse reactions occur at equal rates; concentrations stabilize.

Le Chatelier's principle

At equilibrium, a system counteracts a disturbance by shifting to restore balance.