Chemistry

Intramolecular Bonds


Ionic bond

The ionic bond is a result of the change between ions of opposite electric charges (anions and cations).

This link usually happens between metals and nonmetals.

Metals - 1 to 3 electrons in the last shell; tendency to lose electrons and form cations. More electropositive or less electronegative elements.

Nonmetals - 5 to 7 electrons in the last shell; tendency to gain electrons and form anions. More electronegative or less electropositive elements.

So:

METAL + NON METAL → ION CONNECTION

Example: Na and Cl

Na (Z = 11) K = 2 L = 8 M = 1
Cl (Z = 17) K = 2 L = 8 M = 7


Chlorine wants to receive 7 is in the last layer. To get 8e (equal to the noble gases) you need 1e.

Ionic bonds form ionic compounds that are made up of cations and anions. Such ionic compounds form according to the ability of each atom to gain or lose electrons. This ability is the valence.

Observe the table with the valence of the chemical elements (some alkaline, earth alkaline, calcogen and halogen):

SYMBOL

CHEMICAL ELEMENT

ELECTRICAL CHARGE

At

SODIUM

+1

K

POTASSIUM

+1

Mg

MAGNESIUM

+2

Here

CALCIUM

+2

Al

ALUMINUM

+3

F

FLUORINE

-1

Cl

Chlorine

-1

Br

BROMO

-1

O

OXYGEN

-2

s

SULFUR

-2

Valence of other chemical elements:

SYMBOL

CHEMICAL ELEMENT

ELECTRICAL CHARGE

Faith

IRON

+2

Faith

IRON

+3

Ag

SILVER

+1

Zn

ZINC

+2

Example: Mg and Cl

You can use the “scissor rule”, Where the cation will be the number of chlorines (not metal) in the final formula and the anion will be the number of magnesium (metal).

Another example: Al and O


In this case, the “scissors rule” was also used. The final formula will be called ion formula.

Electronic Formula / Lewis Theory

The electronic formula represents the electrons in the valence layers of atoms.

Ex. NaCl

The electronic formula is also called the formula of Lewis, because it was proposed by this scientist.

Ion Bonding Properties:

- are solid at room temperature and 1atm pressure;
- have high PF and PE;
- are soluble in polar solvents such as water, for example;
- Conduct electricity when in aqueous solution and when fused.