Energy Levels of electrons

Quantum Mechanics theory States that Electrons in any atom can only occupy certain fixed energy levels

When electrons have not absorbed additional outside energy, there are in the "ground state" or lowest energy state

Energy level Characteristics

The highest energy level of each atom corresponds to the now (period) numbers on the periodic table

The electrons in an atom are distributed to the energy levels in order and fill each energy level before starting the next level.

A full energy level is stable The number of elections to be distributed for an element equals the atomic number of that element

Electron Arrangements and Periodic Table

electron distribution always starts with energy level 1.

• All elements other than Hydrogen energy level one is full

Valence Electrons

electrons in full flower) energy levels are stable, they do not take part in the chemistry of an atom

valence electrons are the electrons in the highest (unfilled) energy level for an atom

each atom has 1-8 valence electrons

valence electrons equal the column (Group) number of an element.

• All members of the group have the same number of valence electrons

valence electrons determine the bonding characteristics and physical and chemical properties of an element

Octet Rule

The tendency of atoms to lose or gain electrons or to share electrons with other atoms, to obtain eight total electrons in their upper energy level

Ions

Atoms that gain or lose electrons in order to follow the octet rule

When ions are formed, their highest energy level is full (Nobel Gases)

To determine which ion will form, determine whether adding or losing electrons is easier for the atom

The Charge on the ion equals the number of protons

• number of electrons

Ions have different physical and chemical properties than the neutral element

Noble Gases -Group 8A

full upper energy levels and full octets

stable and unreactive

Atoms form ions to achieve full upper energy

levels just like Group 8A

Ions

Neutral atoms have the same number of protons and electrons and are uncharged

Atoms that add elections now have more elections than protons, become negatively charged and are called Anions

• main group of nonmetals can become Anions

Atoms that lose electrons have fewer elections than protons, become positively charged and are called Cations.

• main group metals

Transition Metal Ions

Can form more than one cation.

Charges are designated by Roman numerals