Study Guide 2 - Atomic Structure and Periodic Table Vocabulary

A set of vocabulary flashcards defining key atomic structure and periodic table concepts from Study Guide 2.

Atomic Mass

The weighted average of the masses of all naturally occurring isotopes of an element.

Isotopes

Atoms of the same element that have the same atomic number but different numbers of neutrons and different mass numbers, such as ${}^{12}_{6}\text{C}$ and ${}^{13}_{6}\text{C}$.

Mass Number

The total number of protons and neutrons in the nucleus of an atom or ion.

Atomic Number

The number of protons in the nucleus of an atom, which identifies the element and determines its order in the Periodic Table.

Nuclear Charge

The total positive charge of an atom's nucleus, which is equal to the number of protons (for example, $+26$ for an iron atom).

Gold Foil Experiment

An experiment where alpha particles bombarded thin gold foil, demonstrating that an atom is mostly empty space with a small, dense, positively charged nucleus.

Proton

A subatomic particle located in the nucleus with a mass of approximately one atomic mass unit ($1\,\text{amu}$) and a unit positive charge.

Neutron

A neutral subatomic particle located in the nucleus with a mass approximately equal to the mass of a proton.

Electron

A negatively charged subatomic particle located in orbitals surrounding the nucleus.

Orbital

A region of an atom that represents the most probable location of an electron.

Bright-Line Spectrum

The characteristic spectrum emitted by an atom when its electrons return from higher energy levels to lower energy states.

Excited State

The state of an atom when an electron gains energy and moves to a higher energy level, represented by electron configurations such as $1s^2 2s^2 2p^5 3s^2$.

s Sublevel

An atomic sublevel containing $1$ orbital that can hold a maximum of $2$ electrons.

p Sublevel

An atomic sublevel containing $3$ orbitals, all having the same shape but different spatial orientations.

d Sublevel

An atomic sublevel containing a total of $5$ orbitals.

Electronegativity

A measure of an atom's ability to attract electrons in a chemical bond.

First Ionization Energy

The amount of energy required to remove an electron from an atom; within any period, alkali metals have the lowest first ionization energy.

Transition Metal Ions

Ions such as $\text{Fe}^{2+}$ or $\text{Ni}^{3+}$ that typically produce colored solutions when present in liquid form.

Chemical Similarity

The characteristic shared by elements located in the same group of the Periodic Table (such as $\text{K}$ and $\text{Na}$, or $\text{Br}$ and $\text{F}$) due to their similar valence electron structures.

Most Active Metals

The elements situated in the lower left corner of the Periodic Table.