COVALENT BONDING

WHERE ELECTRONS ARE SHARED AND ATOMS REMAIN NEUTRAL

IONIC BONDING

ELECTRONS ARE LOST BY METALAND GAINED BY NONMETALS

ATOM IS A METAL

ATOM BECOMES + CHARGED

-ATOM IS A NONMETAL-ATOM BECOMES ----CHARGED

COVALENT BONDINGSHARING OF ELECTRONSATOMS REMAIN NEUTRAL

OCCURS BETWEEN:2 NONMETALS

A NONMETAL AND A METALLOIDHYDROGEN AND ALL NONMETALS

PRODUCES WEAK BONDSPRODUCES COMPOUNDS THAT HAVE LOW

MELTING POINTSALL ORGANIC COMPOUNDS ARE COVALENT

COVALENT BONDINGBETWEEN2 NONMETALS

Nonmetals, because they have more than 4 valence electrons and especially those that have small atomic radii, will bond with them-selves in order to become stable and exist at a lower energy state.

These atoms will be called DIATOMS. There are 7 diatomsThat you will need to memorize. They are F, Cl, Br, I, O, N, H.

COVALENT BONDSBetween hydrogen and A nonmetal

Fluorine has 7 valence electronsIt needs 8 in order to exist in a lowerEnergy state. It could bond ionically With A metal or covalently with hydrogenby sharing one of its valence electrons.

Hydrogen has only one Electron and therefore will neverLose that electron. In order forIt to become stable and existIn a lower energy state, it willShare its only electron withfluorine

COVALENT BONDINGBETWEEN

NONMETAL AND A METALLOIDCarbon will be our only metalloid with 4 valence electrons

Fluorine is a Nonmetal with 7 Valence electrons

The resulting stable cmpdContains 4 F and 1 C. Because the atoms never LOST E’s they remainneutral.

POLARITYUNEVEN DISTRIBUTION OF CHARGESMolecules tend to be asymmetric

__ +

On polar molecules, electrons are controlled by oneOf the atoms.

Nonpolar: even distribution of chargesMolecules tend to by symmetric

Water molecules are polar = the hydrogen side of the molecule ‘feels’ more positiveBecause of the absence electrons. The oxygen side of the molecule ‘feels’ more negativeBecause of the presence of electrons. Here, as in all polar molecules, oxygen has 2 energyShells, making oxygen the ‘larger’ atom. It will control hydrogens’ electrons.

Because oxygen is controlling the electrons shared from hydrogen atoms, the electronsWill circle around oxygen’s nucleus as well as hydrogens’ nuclei.Oxygen’s greater presence of negative charges and energy, will cause the electrons to Be shared unequally=polar.

+ +

_

Intermolecular forces: forces that hold molecules(smallest part of a covalent bond) together.In an ionic bond the opposite charges of the ionshold the compound together. In a covalent bondthere are no opposite charges because electronsare not lost or gained.Hydrogen bonds: forces found between the molecules of the water molecules.

H H H H H H H

O O O O O O

H H H H H H H

Well how does all this connect with solutions? The reason why solutes stay in solutionis because of polarity. Polar solutes dissolve most easily in polar solvents – water is polarand so it can dissolve all polar molecules. Nonpolar solvents dissolve nonpolar solutes.

NaCl

NaCl is an ionic compoundthat is made up of + Naions and - Cl ions.NaClWhen an ionic compounddissolves in water it is called DISSOCIATION.

Na +Na +

Na +

Na +

Na + Na +

Na +Na +

Na +

Na +

Na +

Na +Na +

Na +

Na + Na +

Na +

Cl -

Cl -

Cl -

Cl -

Cl -

Cl -

Cl -

Cl -Cl -

Cl -

Cl -

Cl -

Cl -

Cl -

Cl -

Cl -

Cl - Cl -

Cl -Cl -

If a non polar molecule is put into water, it will NOT dissolve because of the like Charges that will meet in the water and the solute.

CH4 is a symmetricmolecule that is non polar. It will notdissolve in waterbecause it will be repelledby the positive pole ofthe water molecule.

In the water molecule, hydrogen has theability to form 4 bonds-two covalentwith oxygen and two hydrogen bondswith oxygen of another water molecule.Because of this, cohesion, attractionbetween molecules of the same compoundoccurs. We call this kind of attractive force surface tension.

Van der Waal forces: weaker than Hydrogen bonds; found in polar molecules.

Adhesion is the attractive forces actingbetween molecules of different substances

Solutions and suspensions:Solutions: homogenous mixture

solute-substance being dissolved solvent-substance dissolving polarityH H H H H H

O O O O O

H H H H H H

NaCl = Na + & Cl -

Each sodium ion will dissociate (move away from) from the chlorine ion. It is still an ion so itMaintains its charge. Water is polar-hydrogen feeling more positive-oxygen feeling more neg.Ions will ‘stick’ through opposite charges to the polar ends of the water molecule=dissolving.

ClClCl

Cl Cl Cl Cl Cl

ClCl

Na NaNaNa

Suspensions: mixture heterogeneous

Blood: solution: dissolved salts, proteins,

and carbohydratessuspension: blood cells and fat

that are moved along but notdissolved

Acids, bases, salts, buffersAcids: forms H ions in solution.

pH 1-6

Bases: form OH ions in solution pH 8-14

Salts: ionic metal and nonmetal pH 7 = neutral

Buffers: weak acids and bases

Organic compounds: any compound that contains carbon and a specific ratioof hydrogen to oxygen.Because carbon has 4 valence electronsit has the capability of producing multiplebonds with not only other elements butwith itself as well.

Living cells contain molecules that areMade of thousand or hundred of thousandMolecules bonded together.These molecules are called macromoleculesBecause they are so large.These molecules are formed through a process known as polymerization

Four macromolecules found in living cells are: Carbohydrates

Lipids

Proteins:

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html

Proteins:

Nucleic acids:

Reactions:

Dehydration: removal of water to form a compound

Glucose + glucose sucrose + water2 monosaccharides disaccharide

Neutralization: acid + base a salt + water

pH: 1-6 8-14 7 7

Neutral cmpds

Activation energy-energy needed to start a reaction and produce a product.Remember= atoms bond in order to exist at a lower energy state.

=every bond made contains energy

=every bond broken will release energy =every compound needs a specific amount of energy to be formed

A=energy of the reactants B=activation energyC=activated complexD=energy of the products

Reactants-Higher energy

Products-Lower E

Exothermic rxn =Spontaneous rxn

AD

B

C

Energy of reactants is less thanThe energy of the products

Endothermic reaction =

Not spontaneous.