Atomic Structure and Periodic Trends

Vocabulary flashcards covering atomic structure, isotopes, atomic mass, periodic table concepts, and electron configuration.

Atom

The basic structural unit of an element consisting of a nucleus of protons and neutrons with electrons around it.

Nucleus

The center of the atom; positively charged region that contains protons and neutrons.

Proton

A positively charged subatomic particle located in the nucleus.

Neutron

An electrically neutral subatomic particle located in the nucleus.

Electron

A negatively charged subatomic particle located outside the nucleus; electrons orbit the nucleus.

Atomic number (Z)

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

Mass number (A)

The total number of protons and neutrons in the nucleus.

Isotopes

Atoms of the same element (same Z) with different numbers of neutrons (A), leading to different masses.

Atomic mass

The weighted average mass of an element's atoms based on isotopic abundances, measured in amu.

Abundance

The percentage of each isotope of an element found in nature used to calculate atomic mass.

Periodic Law

The physical and chemical properties of the elements are periodic functions of their atomic numbers.

Period

A horizontal row of elements on the periodic table; contains repeating patterns (e.g., 2, 8, 8, 18, 18, 32, 32).

Group (family)

A column of elements in the periodic table; elements in the same group share similar properties.

Metals

Elements with high thermal and electrical conductivity, malleability, and ductility; tend to lose electrons in chemical changes; usually solid at room temperature.

Nonmetals

Elements that tend to gain electrons; poor conductors; can be solids, liquids, or gases; often brittle as solids.

Metalloids

Elements with properties between metals and nonmetals; border the metal–nonmetal divide.

Electron configuration

The arrangement of electrons in atoms described by principal energy levels, sublevels, and orbitals.

Principal energy level (n)

The main energy level of electrons; n = 1, 2, 3, …; higher n means higher energy and electrons farther from the nucleus.

Sublevels (s, p, d, f)

Subdivisions within a principal energy level; include s, p, d, f and hold electrons (2, 6, 10, 14 respectively).

Orbitals

Regions within a sublevel where electrons reside; each orbital holds up to 2 electrons; shapes include s (spherical) and p (dumbbell).

Group (family)

A column of elements in the periodic table; elements in the same group share similar properties.