Atoms and Elements: Structure, Symbols, and the Periodic Table

Atoms and Elements

Introduction to Elements

Elements are the fundamental building blocks of matter. Each element is a pure substance that cannot be broken down into simpler substances by chemical means. The study of elements and their properties is foundational in chemistry.

• Element: A pure substance from which all other things are built. Elements are listed in the periodic table.

• Example: Sulfur (S) and aluminum (Al) are both elements.

Elements and Their Names

Origins of Element Names

Element names are derived from a variety of sources, including planets, mythological figures, minerals, colors, geographic locations, and famous people.

Element	Symbol	Source of Name
Uranium	U	The planet Uranus
Titanium	Ti	Titans (mythology)
Chlorine	Cl	Chloros: "greenish yellow" (Greek)
Iodine	I	Ioiedes: "violet" (Greek)
Magnesium	Mg	Magnesia, a mineral
Tennessine	Ts	Tennessee
Curium	Cm	Marie and Pierre Curie
Copernicium	Cn	Nicolaus Copernicus

Chemical Symbols

Understanding Chemical Symbols

Chemical symbols are standardized one- or two-letter abbreviations for element names. The first letter is always capitalized; if there is a second letter, it is lowercase.

• One-letter symbols: C (carbon), S (sulfur), N (nitrogen), H (hydrogen)

• Two-letter symbols: Co (cobalt), Si (silicon), Ne (neon), He (helium)

• Note: Some symbols are derived from Latin names, e.g., Ag for silver (argentum).

It is important to distinguish between element symbols and chemical formulas. For example, CO represents a compound (carbon monoxide), not the element cobalt (Co).

The Periodic Table

Organization of the Periodic Table

The periodic table arranges all known elements in order of increasing atomic number and groups them by similar chemical properties.

• Groups: Vertical columns (numbered 1-18 or 1A-8A for representative elements)

• Periods: Horizontal rows (numbered 1-7)

• Representative elements: Groups 1A (alkali metals), 2A (alkaline earth metals), 7A (halogens), 8A (noble gases), and others

Metals, Nonmetals, and Metalloids

The periodic table is divided into metals, nonmetals, and metalloids, separated by a zigzag line.

• Metals: Shiny, ductile, malleable, good conductors of heat and electricity, mostly solids at room temperature (except mercury)

• Nonmetals: Dull, brittle, poor conductors, low melting points and densities, can be solids, liquids, or gases

• Metalloids: Properties intermediate between metals and nonmetals; semiconductors (e.g., B, Si, Ge, As, Sb, Te, Po, At, Ts)

Table: Comparison of Metals, Metalloids, and Nonmetals

Property	Metal	Metalloid	Nonmetal
Appearance	Shiny	Varied	Dull
Malleability	Malleable	Brittle or malleable	Brittle
Conductivity	Good	Intermediate	Poor
State at Room Temp	Solid (except Hg)	Solid	Solid, liquid, or gas

Key Terms and Definitions

• Element: A substance that cannot be broken down into simpler substances by chemical means.

• Chemical Symbol: One- or two-letter abbreviation for an element.

• Periodic Table: A chart that organizes elements by increasing atomic number and similar properties.

• Group: Vertical column in the periodic table.

• Period: Horizontal row in the periodic table.

• Metal: Element with high electrical and thermal conductivity, malleability, and luster.

• Nonmetal: Element lacking metallic properties.

• Metalloid: Element with properties intermediate between metals and nonmetals.

Example: Identifying Elements and Symbols

• Given the name: Magnesium → Symbol: Mg

• Given the symbol: Cl → Name: Chlorine

Additional info: The notes above are foundational for understanding atomic structure, chemical bonding, and periodic trends, which are essential topics in GOB Chemistry.