Chemical Bonds
Atom Connections
- Atoms bond (chemical reaction) to become more stable.
- "More Stable" = lower energy (PE) = "more balanced charge"
Review: Bonding
- Involves electrons (e-), which can move
- Usually valence electrons (those in the highest/outermost level)
- How to determine valence electrons:
- Count tall columns of the Periodic Table (PT)
- Electron configuration
Octet Rule
- Atoms gain, lose, or share electrons to achieve a stable octet (8 electrons) in their valence level.
- Hydrogen (H) and Helium (He) are stable with 2 electrons.
Oxidation Number
- Definition: The number of electrons an atom needs to gain, lose, or share to get a stable octet in its valence level.
- It can appear as though an atom has 0 valence electrons, but it might actually give away electrons to have 8 electrons in its next lowest level.
- Atoms do what is "easiest" (least electrons moved) to get 8 electrons in their valence level.
| Element | Valence # (gain/lose) | Oxidation # | Symbol |
|---|
| Cl | gain 1 | -1 | Cl- |
| Na | lose 1 | +1 | Na+ |
| N | gain 3 | -3 | N3- |
| Ca | lose 2 | +2 | Ca2+ |
| S | gain 2 | -2 | S2- |
Terms Recap
- Atom: 1 unit, piece, particle of an element.
- Molecule: 1 unit, piece, particle of elements joined with covalent bonds.
- Shows the ratio of atoms in 1 molecule.
- Strong connections within the particle (bonds).
- Weak connections between particles: Intermolecular Forces (IM forces).
- Formula Unit: 1 unit, piece, particle of elements joined with ionic bonds.
- Shows the ratio of millions+ of atoms.
- 1 part of the crystal pattern.
- Strong connections between ions (ionic bond).