Lecture 2: Basics of Chemistry (Chapter 2)

Vocabulary flashcards covering key terms from the lecture notes on atomic structure, periodic table, bonding, water properties, and pH.

Atom

The basic unit of matter, composed of protons, neutrons, and electrons.

Element

A pure substance that cannot be broken down into simpler substances by chemical means; listed on the periodic table.

Periodic Table

A chart organizing elements by increasing atomic number and group/period properties.

Atomic number

The number of protons in an atom's nucleus; defines the element.

Mass number

The total number of protons and neutrons in an atom's nucleus.

Isotopes

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

Protons

Positively charged subatomic particles in the nucleus; determine atomic number.

Neutrons

Electrically neutral subatomic particles in the nucleus contributing to mass.

Electrons

Negatively charged subatomic particles that orbit the nucleus and determine charge.

Electron shells

Regions around the nucleus where electrons reside; energy increases with distance from the nucleus.

Valence electrons

Electrons in the outermost shell that determine bonding behavior.

Chemical bonds

Attractions that hold atoms together to form molecules; include covalent, ionic, hydrogen, and van der Waals interactions.

Covalent bonds

Bonds formed by sharing electrons between atoms.

Ionic bonds

Bonds formed by transfer of electrons, creating ions that attract each other.

Polar covalent bonds

Covalent bonds where electrons are shared unequally, creating partial charges.

Nonpolar covalent bonds

Covalent bonds with equal sharing of electrons and no partial charges.

Hydrogen bonds

Weak attractions between a slightly positive hydrogen and a slightly negative atom (often O or N) in nearby molecules.

Van der Waals forces

Weak noncovalent interactions arising from transient charge distributions; not true bonds.

Cation

Positively charged ion formed when an atom loses electrons.

Anion

Negatively charged ion formed when an atom gains electrons.

Hydrophilic

Substances that readily dissolve in water; polar or ionic.

Hydrophobic

Substances that do not dissolve well in water; nonpolar.

Amphipathic

Molecules with both hydrophilic and hydrophobic regions.

Dehydration synthesis

A reaction that builds larger molecules by removing a water molecule.

Hydrolysis

A reaction that breaks bonds by adding water.

Solvent

The dissolving medium in a solution; water is a common polar solvent.

Solute

Substances dissolved in a solvent.

pH

A measure of hydrogen ion concentration in a solution; indicates acidity or basicity.