Atomic Structure and Periodic Table Notes

Vocabulary flashcards covering element classifications, periodic trends, atomic structure, isotopes, and electron configurations based on lecture study notes.

Metals

Elements located to the left of the metalloid staircase (except Hydrogen), making up the majority of elements on the periodic table.

Nonmetals

Elements located to the right of the metalloid staircase on the periodic table.

Metalloids (Semimetals)

The staircase of elements separating metals from nonmetals that exhibit both metallic and non-metallic properties.

Atomic Radius

One-half ($\frac{1}{2}$) the distance between two nuclei of adjacent bonded atoms.

Ionization Energy (IE)

The amount of energy required to remove an outer electron from an atom.

Electronegativity (EN)

The tendency of an atom to pull electrons toward itself, rated on a scale of $0.7$ to $4.0$.

Alkali Metals

Elements located in the 1st column of the periodic table; characterized as dull silver, soft, and very reactive.

Alkaline Earth Metals

Metals similar in properties to alkali metals, but harder and less reactive.

Rare Earth Elements

Elements occupying the bottom two rows that are placed separate from the rest of the periodic table.

Basic Metals

Metals located between the transition metals and the metalloids.

Noble Gases

Gaseous, non-reactive nonmetals with a full outer shell of $8$ valence electrons, often used to make "neon" lights.

Halogens

A group of nonmetals that are diatomic, poisonous, and very reactive.

Atomic Number

The number of protons in an atom, which defines the element and equals the number of electrons in a neutral atom.

Mass Number

The total number of protons and neutrons located inside an atom's nucleus ($\text{Protons} + \text{Neutrons}$).

Charge

The net electrical value of an atom determined by the formula $\text{Protons} - \text{Electrons}$.

Isotopes

Atoms of the same element having the same number of protons but a different number of neutrons, resulting in different mass numbers.

Isotopic Mass

The actual mass of an isotope's nucleus, measured in kilograms ($\text{kg}$), grams ($\text{g}$), or atomic mass units ($\text{amu}$).

Full Name Notation

An isotope notation written as the element name followed by a hyphen and its mass number (e.g., Uranium-235).

Symbolic Notation

An isotope notation displaying the chemical symbol, mass number, atomic number, and sometimes the electrical charge (e.g., $^{60}_{27}\text{Co}^{2+}$).

Average Atomic Mass

The decimal number on the periodic table representing the weighted average of the isotopic masses of an element's naturally occurring isotopes.

Protons

Subatomic particles located in the nucleus with a positive ($+$) charge; changing the number of protons changes the identity of the element.

Neutrons

Subatomic particles located in the nucleus that carry no charge ($0$) and provide nuclear glue.

Electrons

Subatomic particles with a negative ($-$) charge located in orbitals or shells outside the nucleus that react and interact with other atoms.

s Orbital

A spherical orbital centered around the nucleus that can hold up to $2$ electrons.

p Orbital

An hourglass-shaped orbital oriented along three axes ($x$, $y$, and $z$) that can hold up to $6$ total electrons across its subshells.

d Orbitals

A set of $5$ orbital sections capable of holding up to $10$ total electrons.

f Orbitals

A set of $7$ orbital sections capable of holding up to $14$ total electrons.

Aufbau Principle

The principle stating that electrons fill the lowest available energy subshells first because they follow the path of least resistance.

Hund's Rule

The rule stating that electrons must enter empty subshells singly before pairing up, and must possess the same spin when occupying separate degenerate orbitals.

Pauli Exclusion Principle

The rule stating that when two electrons occupy the same orbital, they must have opposite spins.

Noble Gas Notation

A shorthand method of writing electron configurations where the preceding noble gas is enclosed in brackets (e.g., $[\text{Ne}]$) and followed by the remaining outer electrons.

Valence Electrons (VE)

The electrons located in an atom's outermost shell or highest occupied energy level.

Valence Electrons and Reactivity

The principle that atoms react to attain a full outer valence shell: atoms with $<4$ valence electrons tend to lose electrons, while atoms with $>4$ valence electrons gain electrons to reach $8$.