Chemistry (Bonding theory and Lewis formulas, Ionic, Moleculer, Vesper structures)

Valence electrons occupying the

Highest energy level

energy-level theory says the the electrons in lower energy levels are held so ___ __by their_____- that, during chemical recation, they remain__

Strongly , Nucleus, Unchanged

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( )

( ) o ( )

A region of space around an atoms nucleus where an electron my exist

Valence orbitals

The volumes of space that can be occupied by electrons in a atoms highest energy level

Bonding electrons

An atom with a valence orbital that is occupied by a single electron and therefore share that electron with another atom.

Lone pair

A full valence orbital with two electrons which has a repeling affect on any nearby orbitals

Quantum mechanics rules

1. The FIRST energy level has room for only one orbital with a maximum of 2 electrons
2. Energy levels above the first have room for FOUR orbitals which is 8 electrons max.

Octet rule

The octet rule is a chemical rule of thumb that reflects the theory that main-group elements tend to bond in such a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas

Atoms that always obey the octet rule when bonding.

C1,N1, O1, F1

Atoms that are exceptions to the octet rule.

NO, SF6, BCl3

Lewis symbol also called

Lewis dot diagram

Rules for drawing lewis symbol

1. Write the element symbol to represent the nucleus
2. Add a dot to represent each valence electron
3. If more than four electrons start filling with a seconf electron

Ionic bond

1. electrostatic attraction between positive and negative ions
2. Metals tend to lose the electrons well non-metals gain

Define electronegativity

relative ability of an atom to attract a pair of bonding electrons in its valence level

The atom with highes electronnegativivty

Fluorine (4.0)

Atom with lowest electronegativity

Francium (0.7)

electronnegativty range

0\.7-4.0

A generalization is that metals have ________ electronegativety while nonmetals tend to have ___ electronegativety

Low, High

Types of bonding

Covalent, Ionic, Metallic

* If the electronegativities of each atom are relatively high, then neither atom “wins” the competition
* Instead the pair of bonding electrons s shared between two atoms and a COVALENT bond forms
* Usually occurs between two non-metal atoms (2C)
* The electron sharing may be unequal (CO)

Covalent bonding

* If the electronegativities of the two atoms are very diffrent, the atom with the higher electronegativitie will “win” and take the bonding electron from the lower electronegativities
* an ___ forms when an electron tansfer occurs
* Occurs between metals and non-metals
* ions arrange themselves in position where the maximum total attraction between positive and ions occur

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Ionic bonding

* If the electronegativities of the colliding atoms are both low, then the atoms share valence electrons in a __ bond.


* The valence electrons are not held strongly by their atoms; so they can move arround
* there will be a large number of positive electrons surrounded by a sea of moving electrons
* this is weak attraction in which the metal atoms are not arranged in any particular arranements, which create that is flexable, malleable, and ductile

Metallic bonding

Scientis figured out that two non-metal atoms must ___ *a pair of elctrons in a* ______ bond

share, covalent bond

Covalent bonds shares one pair of elctrons

single

Covalent bonds shares Two pairs pair of elctrons

double

Covalent bonds shares three pairs of elctrons

triple

Diatomic molecules

O2, CL2, N2, H2, I2, Br2

polyatomic molecules

P4, S8

* Molecular compunds do not have simplest ratio formulas like ionic compounds
* Instead, molecular formulas show the actual number and arrangment of the atoms
* all atomsb strive to fill their valence orbitals with a full octet
* Bonding capacity = max # of single covalent bonds
* in turn, the # of ___ determine an atoms bonding capacity

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Bonding electrons

Coordinate covalent bond

Covalent bond in which pne pf the atoms donates BOTH electrons

o oo

o C o o F o o

o oo

lewis

C-F=H

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Structural

H ---- C _______ C

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H

Stereochemical

2 bond pairs and 0 lone pairs

linear

4 bond pairs and 0 lone pairs

Tetrahedral

3 bond pairs and 0 lone pairs

Trigonal planar

3 bond pairs and 1 lone pairs

Trigonal pyramidal

2 bond pairs and 2 lone pairs

angular

1 bond pairs and 3 lone pairs

Linear tetrahedral

In a ______, the negative (electron) charge is not distributed symmetrically among the atoms making up the molecule.

Polar molecule

In a _______, electron distribution is symetrical

non-polar

Polar molocules

HCL, CO, NH3, NF3, H2O, OCL, CHCL3, C2H5OH

Non-Polar

CL2, N2, CO2, CH4

If the atoms have the same electronegativivty →they attrect shared electrons equally = ________

Non polar covalent bond

For a very large electronegativity diffrence, electrons may be transferred from one atom to another, thus cations and anions may form, and an _____________ will hold the compound together

Ionic bond

If the atoms have diffrent electronegativities → the attraction for electrons is unequal = ____________

Polar covalent bonds

The ____ the electronegativity diffreence, the _____ the bond

Greater, more polar

NP

0\.0 - 0.5

Polar covalent

0\.5 - 1.7

Ionic

1\.7 - 3.3

The existence of a polar bond ______ necessarily mean that you have a polar molecule

not

factors of polarity

shape of molecular and polarity of molecule

in a ________ the bond dipoles will canclel each other out

nonpolar

In a polar molecule, the bond dipoles ______ cancel each other out and will be nonzero molecule dipole, or an overal resilant vetctor

will not

_______ compounds are solube in polar solvents

Polar

_______ compunds are soluble in non-polar solvents

non-polar

____molecular forces = forces attraction and repulsion between molecules

Inter

____molecular forces = forces attraction within a molecule

Intra

when molecules exert weak attractive forces on each other. Intermolecular forces vary over a mcuh wider range and are considerably weaker than the covalent bonds inside a molecule.

Van der waals forces

In Van der waals forces experimental evidence: take _______ to boil water that it does to decompose water

Less energy

In Van der waals forces, intermolecular forces are responisble for what we _______ about molecular substance

physically observe

_______ forces appear to control the physical behaviour of molecular substances

Intermolecular

The atrraction between dipoles is called _____

Dipole-dipole force

dipole-dipole are amoung the _______ intermolecular

weakest

Dipole-Dipole force exists only in ____ molecules

Polar

Fritz london suggested that Van der waals forces was actually two forces

dipole-dipole, london force

Is due to any electron movement within the molecule

momentary dipole

Lond force is between ____ molecules

All

As the number of electrons in the molecule _______, the boiling point increases

increase

more electrons =

greater london force

Isoelectronic

molecules with the same number of electrons

if both are Isoelectronic what do you do?

Use dipole-dipole force

* between mols
* weak
* attration over greater distance
* explains physical changes

Intermolecular

* Within mol
* strong
* attraction over smaller distance
* explain chemical changes

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Intramolecular

a hydrogen nucleus is shared between pairs of electrons on adjacent molecules

Hydrogen bond

For hydrogen bonding to occur, 2 this must be simultaneously true about the molecule structure.

* Hydrogen must be covalently bonded to another very electronegative atom
* there must be at least one lone pair on the atom bonded to the electrons

Only three possible structures show hydrogen bonding

HF, -OH, -NH

H bondingis not really a “bond” like a covalent bond, but rather an attraction _______ molecules

between