Unit 6: Ionic Compounds

What is a bond?

A mutual electrical attraction between the nuclei and valence electrons of different atoms that binds them together.

How can bonds be formed and why do atoms form chemical bonds?

Can be formed by atoms gaining, losing, or sharing electrons. Chemical bonds are formed to become more stable. ONLY valence electrons are used for bonding.

Why do atoms lose or gain electrons?

To satisfy octet (8e- in outershell, H and He are exceptions). Forms 2 kinds of ions- atom that has an electrical charge, cation and anion.

Ionization energy (energy to remove electron from outer shell) and electron affinity (change in energy from added electron to outer shell) in bonding?

High IE, high EA = less likely to give electrons = anion. Low IE, low EA = more likely to give electrons = cation.

Why are trends important?

It’s the REASON why an atom tends to gain or lose electrons. Number of VE determines how many electrons are lost or gained.

Formation of cations

Atoms that lose electrons: Low IE- doesn’t require ton of energy to take an e- away. Low EA- doesn’t readily accept other e- into outer shell. METALS

Transition metals in bonding

forms cations w diff oxidation (charge) states (depends on what it’s bound to). Sometimes will rearrange to have a pseudo-noble gas configuration (full outer shell, but not really).

Formation of anions

Atoms that gain electrons: High IE- requires ton of energy to take e- away, High EA- readily accepts other e- to other shell. HALOGENS AND NONMETALS

Electrostatic force (Coulombic attraction) -

Force of attraction between positively and negatively charged particles.

Crystal lattice

a 3D geometric arrangement of particles where + and - ions surround each other. Ions are packed into a regular repeating pattern that balances the forces of attraction and repulsion between the atoms.