Chemistry Chapter 2 Part 1: Basic Chemistry Overview

Key terms and definitions from the basic chemistry overview in Chapter 2, Part 1, covering matter, energy, atomic structure, bonding, mixtures, reactions, and energy changes.

Matter

Anything that has mass and occupies space; the subject of chemistry and the science of matter and energy.

Chemistry

The science that studies matter and energy.

Solid

A state of matter with a definite shape and definite volume.

Liquid

A state of matter with definite volume but an shape that changes with the container.

Gas

A state of matter with both shape and volume that can change and fill the space available.

Energy

The capacity to do work or put matter into motion.

ATP (Adenosine Triphosphate)

The main energy carrier in the body; continually formed and broken down into ADP.

Kinetic Energy

Energy of motion.

Potential Energy

Stored or inactive energy that can be converted to motion or work.

Chemical Energy

Energy stored in the bonds of chemical substances; released or stored during chemical reactions.

Electrical Energy

Energy from the movement of charged particles (ions) across membranes or within cells.

Mechanical Energy

Energy involved in moving matter; e.g., muscles moving bones.

Radiant (Electromagnetic) Energy

Energy from light and other electromagnetic radiation.

Atom

The smallest unit of an element that retains its unique properties.

Element

A pure substance consisting of one type of atom; cannot be broken down chemically into simpler substances.

Molecule

Two or more atoms bonded together of the same kind (per notes: two or more of the same atom, e.g., O2, H2).

Compound

Two or more different kinds of atoms bonded together.

Isotope

A structural variation of an element with a different number of neutrons.

Atomic Number

The number of protons in the nucleus; identifies the element.

Mass Number

The sum of protons and neutrons in the nucleus.

Atomic Symbol

The one- or two-letter shorthand for an element (e.g., H, He, C, O).

Proton

A positively charged subatomic particle in the nucleus.

Neutron

A neutral subatomic particle in the nucleus.

Electron

A negatively charged subatomic particle that orbits the nucleus in electron shells.

Nucleus

The center of the atom containing protons and neutrons.

Valence Shell/Outer Shell

The outermost electron shell; its electrons determine chemical reactivity and stability.

Octet Rule

Most atoms are most stable with eight electrons in their outer shell (two in the first shell).

Ion

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

Cation

An ion with a positive charge (lost electrons).

Anion

An ion with a negative charge (gained electrons).

Ionic Bond

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

Covalent Bond

A bond formed by sharing electrons between atoms.

Nonpolar Covalent Bond

A covalent bond in which electrons are shared equally, resulting in no partial charges.

Polar Covalent Bond

A covalent bond where electrons are shared unequally, creating partial charges on atoms.

Hydrogen Bond

A weak attraction between molecules (often involving H), contributing to 3D structure and properties like water’s surface tension.

Solution

A homogeneous mixture where solute is dissolved in a solvent.

Solvent

The liquid in which a solute is dissolved (e.g., water in most biological solutions).

Solute

The substance dissolved in the solvent.

Colloid

A heterogeneous mixture with small particles that do not settle and remain dispersed (appears cloudy or milky).

Suspension

A heterogeneous mixture with large particles that eventually settle (visible sediment).

Homogeneous vs Heterogeneous

Homogeneous: uniform composition throughout; Heterogeneous: nonuniform composition with visible separate components.

Synthesis Reaction

An anabolic reaction where smaller reactants combine to form a larger product; bonds are formed.

Decomposition Reaction

A catabolic reaction where a large molecule is broken into smaller pieces; bonds are broken.

Exchange (Displacement) Reaction

A reaction where bonds are broken and new bonds form, with rearrangement of components.

Exergonic

A reaction that releases more energy than it absorbs.

Endergonic

A reaction that absorbs more energy than it releases.

Enzyme

A biological catalyst (protein) that speeds up a chemical reaction without being consumed.

Catalyst

A substance that speeds a chemical reaction without itself undergoing permanent change.