Chem Ch8

Covalent bond — The sharing of outermost shell electrons between two atoms. (atoms form molecules)

Nature: electrostatic reaction between shared electrons and two nuclei

Electrostatic attraction between shared electrons and two nuclei of the bonded atoms.

—Between non metals and non metals.

Diatomic molecules —molecules composed of two atoms, typically of the same element, such as O2 or N2.

• Shared pair of electrons = bond pair

• Pair of electrons outside = lone pair

Molecular formula = Cl2 (number of atoms) Structural formula = Cl — Cl (bond)

• Single bond: —

• Double bond: =

• Triple bond: 三

Stable duplet = 2 electrons / Stable octet = 8 electrons

Examples:

• Common Molecules: Look for common diatomic molecules that form triple bonds, such as nitrogen (N2), which has a triple bond between the two nitrogen atoms.

• Valence Electrons: Check the valence electron counts: atoms involved in triple bonds typically require three pairs of electrons to achieve a stable octet.

names of compounds

• Mono = 1

• Di = 2

• Tri = 3

• Tetra = 4

To find the relative molecular mass of a compound, follow these steps:

1. Formula: Get the compound's formula (like H2O).

2. Atomic Mass: Check the periodic table for each element's mass (H = 1.01, O = 16.00.)

3. Calculate: Multiply each element's mass by how many atoms are in the formula.

   • Example: For H2O:

     • H: 1.01 × 2 = 2.02

     • O: 16.00 × 1 = 16.00

4. Add: Now, add those numbers together.

   • For H2O: 2.02 + 16.00 = 18.02

Formula mass (for all substances) = Relative molecular mass (only applies to molecular substances)

Dative covalent bond

A dative bond is a covalent bond formed by two atoms where both electrons in a shared pair are contributed from the same atom.