Molecules of Life - Week 3 (Fall 2025)

Vocabulary flashcards covering key terms from the Molecules of Life lecture notes.

Dmitri Mendeleev

Father of the Modern Periodic Table; organized elements by increasing mass and grouped similar properties, predicting gaps in the table.

Periodic Table

A chart organizing elements into groups and periods to show relationships in properties and behavior.

Group

Vertical column in the periodic table; there are 18 groups (IUPAC numbering).

Period

Horizontal row in the periodic table; there are seven periods.

IUPAC numbering

System used to name and number the groups (1–18) in the periodic table.

Alkali metals

Group 1 (1A) metals; highly reactive; exclude hydrogen.

Alkaline earth metals

Group 2 (2A) metals; reactive metals in the second column.

Transition metals

Groups 3–12 (the d-block); metals with variable oxidation states.

Halogens

Group 17 (7A); highly reactive nonmetals.

Noble gases

Group 18 (8A); inert gases with complete outer electron shells.

Inner-transition metals

Lanthanides and Actinides; f-block elements often called rare earths.

Lanthanides

Inner-transition metals in the f-block, part of the rare earths.

Actinides

Radioactive inner-transition metals in the f-block.

Main Group Elements

Elements in groups 1A–8A (s and p blocks).

Metals

High luster, malleable, good conductors of heat and electricity; typically high melting points.

Non-metals

Low density and melting points; poor conductors of heat and electricity.

Metalloids

Elements with intermediate properties between metals and nonmetals; border between the two; examples include B, Si, Ge, As, Sb, Te, At.

More metallic vs less metallic trend

More metallic character generally moves down and to the left; less metallic character moves up and to the right on the periodic table.

States of matter

Solids, liquids, and gases—the three fundamental phases of matter.

Vaporization

Liquid to gas; energy absorbed during the phase change.

Condensation

Gas to liquid; energy released during the phase change.

Sublimation

Solid to gas; energy absorbed during the phase change.

Deposition

Gas to solid; energy released during the phase change.

Melting

Solid to liquid; energy absorbed during the phase change.

Freezing

Liquid to solid; energy released during the phase change.

Energy

Ability to do work or produce heat.

Radiant energy

Energy carried by light.

Chemical energy

Energy stored in chemical bonds.

Thermal energy

Energy related to temperature; often referred to as heat.

Electrical energy

Energy due to the motion or position of electric charges.

Mechanical (Kinetic) energy

Energy of motion; KE = 1/2 mv^2.

Work

Force applied to move an object over a distance; Work = Force × Distance.

Heat

Energy transferred between objects due to a temperature difference.

Potential energy

Stored energy due to position; formula: mass × gravity × height.

Kinetic energy

Energy of motion; formula: 1/2 × mass × velocity^2.

Calorie

Amount of energy required to raise 1 g of water by 1°C; 1 Calorie (Cal) = 1 cal; 1 cal = 4.184 J.

Joule

Unit of energy; 1 J = 1 N·m.

Accuracy

How close a measurement is to the true value.

Precision

How close repeated measurements are to each other.

Subatomic particles

Protons, neutrons, and electrons—the basic components of atoms.

Proton

Positively charged particle in the nucleus.

Neutron

Electrically neutral particle in the nucleus.

Electron

Negatively charged particle orbiting the nucleus.

Nucleus

Center of the atom containing protons and neutrons.

Plum pudding model

Thomson’s model: electrons embedded in a positive charge sphere.

Rutherford gold foil experiment

Experiment showing a small, dense nucleus; most alpha particles passed through with few deflections.

Isotopes

Atoms of the same element with the same number of protons but different numbers of neutrons.

Isotopic notation

Notation using mass number A and atomic number Z to denote isotopes (X is element symbol).

Mass number

A; total number of protons and neutrons in the nucleus.

Atomic number

Z; number of protons in the nucleus; defines the element.

Atomic mass unit (amu)

Unit used for atomic and molecular masses; 1 amu is 1/12 the mass of a carbon-12 atom.

Atomic weight

Weighted average mass of naturally occurring isotopes of an element.

Molar mass

Mass of one mole of a substance (g/mol); equals atomic weight for elements.

Formula weight

Mass of one mole of an ionic compound.

Molecular weight

Mass of one mole of a covalent compound.

Avogadro’s number

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

Mole

Amount of substance containing 6.022 × 10^23 particles.

Mass spectrometer

Instrument used to determine exact masses and abundances of isotopes.

H2, Br2, C2H6 (MW examples)

Demonstrates how to calculate molar mass: H2 = 2.02 amu; Br2 = 159.8 amu; C2H6 = 30.08 amu; one mole of C2H6 = 30.08 g.