Chapter 8: Electron Configuration+9: ionic cov bonding

Aufbau Principle

electrons being added into orbitals lowest → highest energy

Pauli Exclusion Principle

No two electrons in the same orbital can have the same spin

Hund’s Rule

Most stable arrangement of electrons w/ max # of unpaired electrons, all with the same spin

Diamagnetism? Paramagnetism? Ferromagnetism?

Diamagnetism - VERY weakly repelled by magnet; requires all electrons paired

Paramagnetism - Weakly attracted to magnet; requires unpaired electrons

Ferromagnetism - STRONGLY attracted to magnet; requires unpaired electrons

Valence Electrons

Electrons that exist outside orbitals, determining chemical properties of an atom

Core electrons

Non valence electrons

What’s effective nuclear charge and symbol?

Symbol: Z

Nuclear charge experienced by electron density in multi electron atom. Core electrons shield the valence electrons from the positive charge of the nucleus.

Equation of Effective Nuclear Charge

Z_estimate = Z (nuclear charge) - core

Larger Z = increased attraction of electrons to nucleus

Ionization Energy

Energy needed to remove electron from atom

Atomic Radius

Distance between nuclei or neighboring atoms

Ca,Ba are largest

Electron Affinity

Energy released when atom gains electrons

Electronegativity

atoms ability to attract and hold shared electrons in bonds

Fluorine, N, O are really electronegative

Structure

the way atoms are arranged in space

Lewis electron dot symbols

standard notation for describing bonding properties of atoms

Ionic Bond

Forms when 1+ VE are transferred from 1 atom to another- creating positive and negative ions

Covalent bonds

Form when atoms share electrons and are responsible for bonds inn molecules and polyatomic ions

How to calculate anions and cations to VE?

anions → add # of electrons to valence orbitals

cations → remove # of electrons to valence orbitals

Ion sizes of cations and anions

anions → larger than neutral atom

cations → smaller than neutral atom

What happens when you remove electrons in transition metals

Electrons removed from 4s before 3d

Octet Rule

Many atoms share electrons until reaching octet of 8 electrons in order to achieve stable noble gas configuration

Bond pair

electrons in bond

Lone pair

electrons not involved in a bond; aka non-bonding e-

Resonance

quantum mechanical wave like effect; similar but different in structure; diff properties possible

Bond order

avg number of bond pairs shared by two atoms in a molecule

Bond length

distance between nuclei of two bonded atoms

bond order and bond length are

proportional — if one decreases so does the other, if one increases so does the other

Electroneutrality Principle

In best resonance structures, formal charges on all atoms are ~0

Negative formal charges mainly on more electronegative atoms

Formal charge and how to calculate

Prediction/assumption of electron charge surrounding an atom in Lewis structure; assumes that all electrons shared equally in atoms (a model)

Formal charge = # of VE - # of lone pair - # of bond pair

Sum of formal charge must EQUAL charge on molecule/ion

Exceptions to octet are

Odd e- species: NO/NO₂

Extra e- species (3rd period+): XEF₄ , SO₄^2-