Ch.4 Chem.

Chemistry ch.4

Democritus

• 
• First person to devolop the concept of an atom

10

• is the amount of electrons sublevel d can hold

sublevel S

• is found in all principal energy levels
• 

Anion

• Negatively charged ion
• 

Folie 6

• Experiments with cothode rays aided in the discovery of electrons

Atomic mass

• The mass of an atom expressed in atomic mass units, the weighted average of all naturally occuring isotopes
• 

A=Z+N

• formula for calculating mass number

Abufbau principle

• 
• The principle that the electron configuration of an atom builds on those of lower atomic number.

bohr model

• 
• planetary model of an atom

Hund's rule

• The rule stating that all electrons in each fill a sub level by placing a single electron orbital before adding a second electron to any orbital.

Kalton's atomic theory