gen chem 1 chapter 3

Paulis exclusion principle

• no two electrons in an atom can have the same set of four quantum numbers

• In a single orbital, electrons must have different spins

Hunds Rule

• bus rule

• fill unoccupied orbitals before pairing electrons

Aufbau Principle

• fill low energy orbitals first

Transition Metal electron configurations

are characterized by the presence of d electrons that can occupy multiple energy levels, often resulting in complex bonding and oxidation states

would rather a filled (or semi filled) d orbital than s to minimize energy and achieve stability.

Core electrons

noble gas configuration, not involved in chemical bonding

Valence e-

are the outermost electrons of an atom, involved in chemical bonding and reactions.

Paramagnetic

describes substances with unpaired electrons, resulting in attraction to external magnetic fields.

dimagnetic

describes substances with all paired electrons, resulting in no net magnetic moment and no attraction to external magnetic fields.

metals

• malleable and ductile

• lusterous apperance

• good electric conductors

• tend to form cations

• solid @ room temp

non metals

• brittle

• dull apperance

• poor heat/electric conductors

• tend to form anions

metalloids

• have properties intermediate between metals and nonmetals

• semiconductors of electricity

• can be brittle and lusterous

• staircase on periodic table

alkali metals

• highly reactive metals

• soft and low-density

• found in Group 1 of the periodic table

• readily lose one electron to form cations

alkaline earth metals

• reactive metals found in Group 2 of the periodic table

• have two valence electrons

• form cations by losing two electrons

• generally harder and denser than alkali metals

halogens

• highly reactive nonmetals

• found in Group 17 of the periodic table

• exist as diatomic molecules in their elemental form

• readily gain one electron to form anions

noble gas

• nonreactive gases found in Group 18 of the periodic table

• have a complete set of valence electrons

• generally exist as monoatomic gases in their elemental form

ionic radius

• measure of an ion's size, defined as the distance from the nucleus to the boundary of the surrounding cloud of electrons.

• cations are smaller than their parent atoms, while anions are larger.

• more positive=smaller size

• largest atoms bottom left of periodic table

ionization energy

• the energy required to remove an electron from an atom or ion in the gas phase.

• generally increases across a period and decreases down a group in the periodic table.

electron affinity

• the energy change that occurs when an electron is added to a neutral atom in the gas phase. It can be either positive or negative, indicating whether energy is released or absorbed.