bonding unit

ionic compound

A compound formed by the transfer of valence electrons between a cation and an anion.

total charge in an ionic compound

The total positive charge must be equal to the total negative charge in the compound.

types of ions in ionic compounds

Monoatomic ions (from the periodic table) or polyatomic ions.

steps for drawing ionic dot diagrams

1. Start with the Lewis Structure (valence electron dots) for each element. 2. Metals transfer electrons to nonmetals until both are stable. 3. Add more metal or nonmetal atoms for complete transfer. 4. Draw resulting ions.

three possible ionic crystal shapes

Face Centered Cubic, Body Centered Cubic, Tetragonal.

Face Centered Cubic shape determination

Same charge, same size (same row).

Body Centered Cubic shape determination

Same charge, different sizes (different rows).

Tetragonal shape determination

Different charges.

molecular compound

A compound formed by the sharing of valence electrons between two nonmetals.

molecular shape determination

VSEPR Theory (Valence Shell Electron Pair Repulsion).

molecular shape with 2 areas of negativity

Linear.

molecular shape with 3 bonds and 0 lone pairs

Trigonal Planar.

molecular shape with 2 bonds and 1 lone pair

Bent 120°.

molecular shape with 4 bonds and 0 lone pairs

Tetrahedral.

molecular shape with 3 bonds and 1 lone pair

Trigonal Pyramidal.

molecular shape with 2 bonds and 2 lone pairs

Bent 109.5°.

bond type based on electronegativity (ionic bond)

≥ 2.0.

bond type based on electronegativity (polar covalent bond)

0.5 - 1.9.

bond type based on electronegativity (nonpolar covalent bond)

≤ 0.4.

intermolecular forces and states of matter (nonpolar)

Repel each other → usually gases at room temp.

intermolecular forces and states of matter (ionic)

100% polar → usually solids at room temp.

intermolecular forces and states of matter (polar molecular compounds)

Usually liquids at room temp.

molecule polarity rules (all nonpolar bonds)

Molecule is nonpolar.

molecule polarity rules (polar bonds & symmetrical)

Molecule is nonpolar.

molecule polarity rules (polar bonds & NOT symmetrical)

Molecule is polar.

symmetrical molecular shapes

Tetrahedral, Trigonal Planar, Linear (with 2 bonds).

naming molecular compounds

Add a prefix to indicate number of atoms, change the second element to '-ide', NEVER use 'mono-' on the first element.

naming ionic compounds with a transition metal

Name first element, Roman numeral for charge, name anion (change to '-ide' for single element or use polyatomic name).

naming ionic compounds without a transition metal

Name cation (no changes), name anion (change to '-ide' or use polyatomic name).

determining type of compound (molecular)

Name has a prefix on the second element.

determining type of compound (ionic with transition metal)

Name includes a Roman numeral.

determining type of compound (ionic without transition metal)

No prefixes, no Roman numerals.

writing formulas for molecular compounds

Prefix indicates number of atoms; no need to balance charges!

writing formulas for ionic compounds

Look up charges, adjust ratio for equal total positive and negative charge.