CHEM 10013 Lecture Notes Review: Chapter 1–2 (Introduction to Chemistry; Atoms and Molecules)

Key vocabulary terms and their definitions from Chapter 1–2 topics, including matter, units and measuring, atomic theory, ions, bonds, and introductory nomenclature.

Matter

Anything that occupies space and has mass.

State

The physical form of matter (solid, liquid, or gas).

Physical properties

Properties observed without changing the substance’s composition (mass, density, boiling point, color, etc.).

Chemical properties

Properties describing how a substance changes chemically (e.g., corrosion, combustion).

Physical change

A change that alters appearance or state but not the substance’s identity.

Chemical change

A change that alters the composition of matter; atoms rearrange to form new substances.

Observation

Information obtained through sensing or measurement.

Hypothesis

A testable, educated educated guess about a phenomenon.

Law

A concise statement that describes a consistent natural phenomenon.

Theory

A well-substantiated explanation of natural phenomena.

Inductive reasoning

Generalizing from specific observations to broader conclusions.

Deductive reasoning

Using general statements to reach specific, logical conclusions.

Unit

A standard quantity used to specify measurements.

SI system

International System of Units—the modern metric system used in science.

Prefix multipliers

Prefixes that scale units by powers of ten (kilo-, milli-, etc.).

Kelvin

The absolute temperature scale used in science; 0 K is absolute zero.

Absolute zero

The lowest possible temperature where molecular motion virtually stops.

Significant figures

Digits that carry meaning in a measurement, with one estimated digit.

Exact numbers

Numbers with unlimited significant figures (counts, defined constants).

Dimensional analysis

A method to convert units using conversion factors.

Conversion factor

A fraction equal to a unit equation used to convert from one unit to another.

Density

Mass per unit volume (d = m/v); can be used as a conversion factor.

Indium tin oxide (ITO)

A doped semiconductor that is highly conductive, optically transparent, and cheap; used in capacitive touchscreens.

Proton

Positively charged subatomic particle in the nucleus; mass ~1 amu.

Neutron

Electrically neutral subatomic particle in the nucleus; mass ~1 amu.

Electron

Negatively charged subatomic particle outside the nucleus; very small mass.

Atomic number

The number of protons in an atom’s nucleus; identifies the element.

Mass number (A)

Total number of protons and neutrons in the nucleus.

Isotope

Atoms of the same element with different numbers of neutrons.

Natural abundance

Relative percent of each isotope found in a naturally occurring sample.

Atomic mass (average atomic weight)

Weighted average mass of an element’s isotopes based on natural abundance.

Ion

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).

Ionic bond

Bond formed by electrostatic attraction between oppositely charged ions.

Ionic compound

Compound composed of cations and anions held together by ionic bonds; forms a formula unit.

Formula unit

The smallest electrically neutral collection of ions in an ionic compound.

Binary ionic compound

Ionic compound containing a metal cation and a nonmetal anion.

Type I vs Type II ionic compounds

Type I: metal forms one common cation; Type II: metal forms multiple cations requiring charge specification.

Polyatomic ion

An ion made of two or more atoms bonded together with an overall charge.

Oxyanion

Polyatomic anion containing oxygen; endings -ate or -ite indicate different oxygen counts.

-ate / -ite endings

Suffixes used to distinguish oxyanions with more or fewer oxygens.

Hypo- / Per- prefixes

Prefixes for oxyanions: hypo- = fewer O, per- = more O in a series.

Covalent bond

Bond formed by sharing electrons between nonmetals.

Molecular compound

Compound composed of nonmetals held together by covalent bonds.

Empirical formula

The simplest whole-number ratio of atoms in a compound.

Molecular formula

The actual number of each type of atom in a molecule.

Structural formula

Diagram showing how atoms are connected and bonded.

Diatomic elements

Elements that exist naturally as diatomic molecules: H2, N2, O2, F2, Cl2, Br2, I2.

Hydrocarbon

Organic compound containing only carbon and hydrogen.

Alkane

Hydrocarbon with only single bonds; suffix -ane.

Alkene

Hydrocarbon with at least one C=C double bond; suffix -ene.

Alkyne

Hydrocarbon with at least one C≡C triple bond; suffix -yne.

Prefixes for hydrocarbons

Mono-, di-, tri-, etc.; indicate the number of carbon atoms.

Functional group

A reactive group in organic molecules that determines chemical behavior.

Alcohol

Organic compound with -OH group; suffix -ol.

Ether

Functional group R-O-R'; common ether name ends with -ether.

Aldehyde

Carbonyl group at the end of a carbon chain; suffix -al.

Ketone

Carbonyl group within a carbon chain; suffix -one.

Carboxylic acid

Organic acid with -COOH group; suffix -oic acid.

Ester

Organic compound with -COO- group; suffix -ate.

Amine

Organic compound with -NH2 group; suffix -amine.

Mono- prefix (omitted sometimes)

Indicates one atom of the first element in a binary molecular compound; often omitted.

Inorganic nomenclature flowchart

Guides naming by whether the compound is ionic or molecular; acids are special cases.

Metals

Elements that are good conductors, malleable, ductile; tend to lose electrons.

Nonmetals

Elements that are poor conductors; tend to gain electrons.

Metalloids

Elements with mixed properties; often semiconductors.

Diatomic elements (overview)

H2, N2, O2, F2, Cl2, Br2, I2—elements that form diatomic molecules.

Atomic elements vs molecular elements

Atomic elements exist as single atoms (e.g., Na, Ne); molecular elements exist as molecules (e.g., O2, N2).