8th Grade Science Study Guide: The Periodic Table

Vocabulary flashcards covering atomic structure, periodic table organization, main element categories, and specific group families based on the 8th grade science study guide.

Periodic Table

An organized chart containing all known elements, which arranges elements based on their atomic structure and chemical properties in increasing order of their atomic number.

Element

A pure substance made of only one type of atom.

Dmitri Mendeleev

The scientist who created the first version of the Periodic Table in 1869, leaving gaps for undiscovered elements.

Atomic Number

The number of protons in an atom's nucleus, which also equals the number of electrons in a neutral atom.

Chemical Symbol

A 1- or 2-letter abbreviation for an element, where the first letter is ALWAYS capitalized, and the second letter (if present) is ALWAYS lowercase.

Atomic Mass

The average weight of an atom's nucleus, calculated as $\text{Protons} + \text{Neutrons}$.

Neutrons Calculation

The formula to find the number of neutrons in an atom, which is $\text{Atomic Mass (rounded)} - \text{Atomic Number}$.

Groups (Families)

Vertical columns (1 to 18) on the periodic table containing elements that share similar chemical properties and the same number of valence electrons.

Periods

Horizontal rows (1 to 7) on the periodic table containing elements that share the same number of electron energy levels (shells).

Valence Electrons

The outermost electrons in an atom.

Metals

Elements located on the left and center of the periodic table that are shiny (luster), good conductors of heat/electricity, malleable, ductile, and mostly solids at room temperature (except Mercury).

Nonmetals

Elements located on the far right of the periodic table that are dull, poor conductors (insulators), brittle, and mostly gases at room temperature.

Metalloids / Semimetals

Elements located along the zigzag line that have characteristics of both metals and nonmetals, and function as semiconductors.

Alkali Metals

Group 1 extremely reactive metals that are soft enough to cut with a butter knife and are never found alone in nature.

Alkaline Earth Metals

Group 2 highly reactive metals, though slightly less reactive than Group 1.

Transition Metals

Groups 3–12 typical hard, shiny metals like Iron, Copper, Silver, and Gold.

Halogens

Group 17 elements that are the most reactive nonmetals and are great for killing bacteria.

Noble Gases

Group 18 non-reactive ("inert") gases that do not readily react because their outer electron shells are full.