Ionic, covalent: polar & non-polar bonds

GROUP 120 – NATALIA DAENNA GONZÁLEZ VIERA, VALERY SELENE GARCÍA MORALES, ANETTE MONTSERRAT SALAZAR ESQUIVEL, LUIS ROBERTO GONZÁLEZ GUAJARDO, EDUARDO ORTEGA CORPUS.

UNIVERSIDAD AUTÓNOMA DE NUEVO LEÓN PREPARATORIA No.9 CHEMISTRY I

ORGANIZATION ACTIVITY

“IONIC, POLAR AND NON-POLAR COVALENT BONDS”

VALENCE ELECTRONS BEHAVIOR COVALENT BONDING

IONIC BONDING

Bonding between non-metals consists of two electrons shared between two atoms. In covalent bonding, the two electrons shared by the atoms are attracted to the nucleus of both atoms. Neither atom completely loses or gains electrons as in ionic bonding.

There are two types of covalent bonding: 1. Non-polar bonding with an equal sharing of electrons.

2. Polar bonding with an unequal sharing of electrons. The number of shared electrons depends on the number of electrons needed to complete the octet.

NON-POLAR COVALENT BONDING Results when two identical nonmetals equally share electrons between them.

• A bond between 2 nonmetal atoms that have the same • One or more atoms lose electrons and electronegativity and therefore have equal sharing of the other atoms gain them in order to bonding electron pair produce a noble gas electron configuration • Complete transfer of valence electron(s) between atoms and is a type of chemical bond that generates two oppositely charged ions.

POLAR COVALENT BONDING Results when two different nonmetals unequally share electrons between them.

• A bond between 2 nonmetal atoms that have different electronegativities and therefore have unequal sharing of the bonding electron pair

KIND OF ELEMENTS THAT COMPOSED IT IONIC BONDING

COVALENT BONDING NON-POLAR COVALENT BONDING

• Typical of ionic bonds are those in the alkali halides • Ionic bonds occur between metals and non-metals on the periodic table.

Turn to your periodic table and examine the three columns headed by Li (ignore hydrogen, if it is there), Be, and B. These columns provide most (not all) of the positive partners involved in ionic bonding.

The first column (called the alkali metals) has Li, Na, K, Rb, Cs, and Fr (teachers tend to ignore Fr because it is so radioactive none exists in nature. All these guys go +1 in ionic bonding.

The second column (called the alkaline earth metals) has Be, Mg, Ca, Sr, Ba and Ra. All of them go +2 in ionic bonding.

The third column is headed by B, but usually the only atom of interest is Al and its charge of +3. An example ionic compound might be

Examples of nonpolar molecules include: • any of the noble gases: He, Ne, Ar, Kr, Xe • any of the homonuclear diatomic elements: H2, N2, O2, Cl2 • carbon dioxide - CO2 • benzene - C6H6 • carbon tetrachloride - CCl4 • methane - CH4 • ethylene - C2H4 • hydrocarbon liquids, such as gasoline and toluene • most organic molecules

POLAR COVALENT BONDING Examples of polar molecules include: • water - H2O • ammonia - NH3 • sulfur dioxide - SO2

AlCl3. The other elements in this column exhibit such complex patterns of behavior that they tend to get ignored.

That does it (for the moment) for the positives, guys and gals. Now, on to the negatives.

Look to the column headed by F and below it, you'll see Cl, Br, I and At. (You can "ignore" At for the same reason as Fr given above.)

These elements will all gain one electron in ionic bonding and will therefore be negative one.

The next column to the left is headed by O. The most common examples used from this column are O and S. Se and Te get used sparingly. Gaining two electrons makes these atoms become a negative two charge in ionic bonding.

Finally, the column with N at the top and P just below. These guys will go -3 in ionic bonding.

As and Sb are rare in high school examples and Bi is never seen as a negative three. • All transition metals and rare earth metals act as positives in ionic bonding.

SCHEMATIC REPRESENTATION IONIC BONDING

COVALENT BONDING NON-POLAR COVALENT BONDING

POLAR COVALENT BONDING

COMPOUNDS FORMED IONIC BONDING

COVALENT BONDING NON-POLAR COVALENT BONDING

• Ionic compounds form crystals.

Ionic compounds form crystal lattices rather than amorphous solids. Although molecular compounds form crystals, they frequently take other forms plus molecular crystals typically are softer than ionic crystals.

• When naming ionic compounds, the cation retains the same name as the element. The anion's name is similar to the elemental name, but the ending of the name has been removed and replaced with "-ide."

IODINE: Iodine forms a diatomic non-polar covalent molecule. The graphic on the top left shows that iodine has 7 electrons in the outer shell. Since 8 electrons are needed for an octet, two iodine atoms EQUALLY share 2 electrons.

OXYGEN: Here are examples of ionic bonds and ionic compounds: Molecules of oxygen, present in NaBr - sodium bromide about 20% concentration in air are KBr - potassium bromide also a covalent molecules . See the NaCl - sodium chloride graphic on the left the Lewis symbols.

NaF - sodium fluoride There are 6 electrons in the outer KI - potassium iodide shell, therefore, 2 electrons are KCl - potassium chloride CaCl2 - calcium chloride needed to complete the octet. The K2O - potassium oxide two oxygen atoms share a total of MgO - magnesium oxide four electrons in two separate bonds, • You can recognize ionic compounds because they called double bonds. consist of a metal bonded to a nonmetal.

The two oxygen atoms equally share the four electrons.

POLAR COVALENT BONDING WATER: Water, the most universal compound on all of the earth, has the property of being a polar molecule. As a result of this property, the physical and chemical properties of the compound are fairly unique.

Hydrogen Oxide or water forms a polar covalent molecule. The graphic on the left shows that oxygen has 6 electrons in the outer shell. Hydrogen has one electron in its outer energy shell. Since 8 electrons are needed for an octet, they share the electrons.

However, oxygen gets an unequal share of the two electrons from both hydrogen atoms.

Again, the electrons are still shared (not transferred as in ionic bonding), the sharing is unequal. The electrons spends more of the time closer to oxygen. As a result, the oxygen acquires a "partial" negative charge.

At the same time, since hydrogen loses the electron most - but not all of the time, it acquires a "partial" charge. The partial charge is denoted with a small Greek symbol for delta.

PHYSICAL PROPERTIES IONIC BONDING

COVALENT BONDING 1.

2.

3.

4.

1. Crystalline solids (made of ions) 2. High melting and boiling points 3. Conduct electricity when melted 4. Many soluble in water but not in nonpolar liquid

Gases, liquids, or solids (made of molecules) Low melting and boiling points Poor electrical conductors in all phases Many soluble in nonpolar liquids but not in water

NON-POLAR COVALENT BONDING

POLAR COVALENT BONDING

The strength of the London dispersion forces depends on the size (length if chain) of the molecule.

If a molecule has very strong intermolecular forces, then....

• That molecule will have a higher boiling point.

• That molecule will have a higher viscosity.

• That molecule will have a lower vapor pressure.

If a molecule has very weak intermolecular forces then..

• That molecule will have a lower boiling point.

• That molecule will have a lower viscosity.

• That molecule will have a higher vapor pressure.

DAILY USED PRODUCTS IONIC BONDING

COVALENT BONDING NON-POLAR COVALENT BONDING

toothpaste tube detergent table salt rock salt rust

Gasoline Teflon Styrofoam cooking oil Crisco margarine motor oil polyethylene candle wax

POLAR COVALENT BONDING

water ammoniac carbon dioxide