Chemistry Notes: Periodic Table Trends, Group Properties, Bonding and Nomenclature

Periods on Periodic Table

Horizontal rows on the periodic table.

Groups on Periodic Table

Vertical columns on the periodic table.

Metals (properties)

Good conductors of heat and electricity; typically ductile; mostly solids (found on the left/molded area).

Nonmetals (properties)

Insulators; not good conductors of heat or electricity; can be gases at room temperature; brittle; not ductile (found on the right side).

Alkali metals (Group 1)

Highly reactive; form salts with halogens (e.g., Na forms NaCl with Cl).

Halogens (Group 17)

Salt-forming elements; typically form one bond with alkali metals to give salts; highly reactive.

Noble gases (Group 18)

Chemically inert/inactive; little tendency to form bonds.

Atomic Radius Trend Across a Period (Left to Right)

Generally decreases.

Atomic Radius Trend Down a Group (Top to Bottom)

Generally increases.

Naming Metal + Nonmetal Compounds (Rule 1)

Name the metal first (cation), then the nonmetal, changing its ending to -ide (e.g., NaCl is sodium chloride).

Naming Two Nonmetal Compounds

Use prefixes (di-, tri-, etc.) to indicate the number of atoms (e.g., $NO_2$ is nitrogen dioxide; $N_2O_5$ is dinitrogen pentoxide).

Chemical Property

A property observed when a substance undergoes a chemical change (e.g., sodium reacting violently with water).

Physical Property

A property observed without changing the substance's chemical identity (e.g., melting point of sodium).

The first 20 elements to memorize

Hydrogen (H), Helium (He), Lithium (Li), Beryllium (Be), Boron (B), Carbon (C), Nitrogen (N), Oxygen (O), Fluorine (F), Neon (Ne), Sodium (Na), Magnesium (Mg), Aluminium (Al), Silicon (Si), Phosphorus (P), Sulfur (S), Chlorine (Cl), Argon (Ar), Potassium (K), Calcium (Ca).