Chem CH 6

Valence electrons

e- in the highest energy level
**the number of valence e- in the representative elements = to the group number (ex: 1A has 1 valence e-)**

Metallic Bond

attraction between metallic cations and free-flowing valence electrons

1. described as a “sea of electrons”

2. allows for of many the physical traits of metals such as:

   a. ductile

   b. malleable

   c. good conductor

Crystalline

repeating pattern

Body Centered Cubic

9 atoms/ 1 atom at each corner cube and 1 atom in a center of a cube

ex. Cr, Na, K, Fe

Face Centered Cubic

14 atoms/ 1 atom at each corner of cube and 1 atom on each face of cube

ex. Au, Al, Pb

Hexagonal Close- Packed

total of 10 atoms/ hexagon with 1 atom in a center then a triangle

ex. Zn, Mg, Cd

Brass

Cu+Zn; Substitutional; more durable

Bronze

Cu+Zn+Sn; Substitutional; reduces rust

Sterling Silver

Cu+Ag; Substitutional; improve conductivity

Stainless Steel

Fe+Cr+Ni; Interstitial; improve appearance

Cast Iron

Fe+ C; reduces cost; interstitial

Octet Rule

when forming cmpds, atoms tend to achieve the e- configuration of a noble gas

Atoms

electrically neutral because: p+ = e-

Ions

atoms that are charged

Cations

any atom or group of atoms with a “+” charge; formed when e- are lost

Anion

any atom or group of atoms with a “-” charge; formed when e- are gained

Ionic Bond

attraction between oppositely charged ions (cation + anion);

• solids @ room temp (mostly white powders)

• high melting points due to strong ionic bond

• good conductors when dissolved or melted

• MUST BE ELECTRICALLY NEUTRAL

• must be written as a formula unit

formula unit (FU)

lowest whole number ratio

Binary Ionic Compounds

composed of only 2 elements

Monatomic Ions

Cations or Anions

Polyatomic Ions

tightly bound groups of atoms that behave as a single unit and carry a single charge; end in -ite or -ate

Ternary Ionic Compounds

contain atoms of 3 different elements; contain one or more polyatomic ions