1. Bonding

2. Chemical Bond
Electrical attraction between nuclei and valence electrons of different atoms that bind the atoms together
Compounds form by gaining, losing, or sharing electrons, to lower their potential energy (PE).
Bond type based on differences in electronegativity values between atoms.
(Sliding scale between purely covalent to purely ionic (we will discuss this further later in the chapter))

3. Molecular (Covalent) Compounds
Composed of nonmetals only
Neutral
Covalent bond: bond created by SHARING electrons between two or more nonmetals
A chemical formula of covalent compound: molecule
Weak intermolecular forces BETWEEN molecules
Can exist as solid, liquid, gas
Relatively low MP and BP
Exist as individual molecules

5. Bond energy: energy required to BREAK chemical bond
Bonds form to lower potential energy (PE)
Electron from one atom attracts proton of another
Nuclei and electrons repel
Forces cancel and bond formed with lower PE than each originally had
Bond formation
RELEASES ENERGY

6. Ionic Bond
Formed when electrons are TRANSFERRED from one atom to the other
Ionic compound:
Cation + anion
Electrically Neutral
(numbers of + charges = numbers of – charges)
Hard, brittle solids
High MP and BP
Conduct electricity when molten (melted) or dissolved in water
Chemical formula of ionic compound: formula unit
Crystal lattice (a 3-D network of cations and anions strongly electrostatically attracted to each other).
Non conductive in solid state bc ions are not free to move, they’re bound together in the lattice structure
Ions minimize potential energy by combining in a crystal lattice.
Attractive forces exist between oppositely charged ions.
Repulsive forces exist between like-charged ions
Attractive and repulsive forces determine:
distances between ions
pattern of the ions’ arrangement in the crystal

7. Ions minimize potential energy by combining in a crystal lattice.
Attractive forces exist between oppositely charged ions.
Repulsive forces exist between like-charged ions
Attractive and repulsive forces determine:
distances between ions
pattern of the ions’ arrangement in the crystal

8. Ionic Vs. Covalent Bonding

9. Melting and Boiling Points of Compounds

10. The Metallic-Bond Model
Metallic bonding: results from attraction between metal atoms and the surrounding sea of electrons
How metallic bonding works:
Vacant orbitals overlap.
Allows outer e- to roam freely
Electrons are delocalized
Forms sea of electrons around the metal ions, which are packed together in a crystal lattice.
The unique characteristics of metallic bonding gives metals characteristic properties:
electrical and thermal conductivity
malleability
ductility
shiny appearance
(they do not belong to any one atom but move freely through the empty atomic orbitals)

11. Properties of Substances with Metallic, Ionic, and Covalent Bonds