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Chemical Bonding Help

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By — McGraw-Hill Professional
Updated on Aug 28, 2011

Introduction to Chemical Bonding

Most elements are attracted to each other in a variety of ways. At the most basic level, protons, neutrons, and electrons are attracted in and around the nucleus by electrical attraction. Cutting-edge chemistry has discovered many subparticles smaller than these basic building blocks with additional attractive forces. A few hold outs, such as some of the noble gases, are unreactive in nature, but can be forced to share brief reactions.

A chemical bond is the relationship between atoms within a molecule. The bonds are made through the interaction of electrons.

Ionic Bonding

One way to think of ionic bonds is to think of a direct gift; the total transfer of electrons between substances. When a metal forms an ionic bond with a non-metal, electrons are transferred from one element to another. When ions are formed, it is called ionization .

Ions are held by electrical attraction, sometimes called electrostatic attraction . This is like when socks stick together when they come out of the electric dryer. The molecules all tumbled together with the addition of heat create ionization. The same thing happens when you rub a rubber balloon on your head. Your hair proteins interact with the molecules of the rubber and electrostatic charge builds up. Try it!

As a general rule, ionic bonds occur between a metal and a non-metal. Covalent bonds occur between two non-metals. Metallic bonds form between two metal atoms.

Examples

A simple, ionic bond between a non-metal and a metal occurs in the formation of ordinary table salt, sodium chloride.

Na + Cl ⇒ Na + Cl + energy

Oxidation of sodium happens when it loses electrons in the reaction, contributing to the ionization, and chlorine is reduced when it gains electrons in the reaction. As the transfer of the sodium electrons to the chlorine ion occurs, the ionic compound is formed. The positive (+) and negative (–) opposite charges attract and form an ionic bond.

Covalent Bonding

The sharing of an electron pair such as in covalent bonding is a great idea from an element’s standpoint. It allows many more reactions to take place than would normally be possible. Remember, according to the octet rule the electrons in a shell must be filled by pairs to get a stable compound.

Table 13.1 compares and contrasts ionic and covalent bonding.

A covalent bond would not work without a contribution from one of the partners in a reaction. However, if a transfer of electrons does not occur, then sharing is an option.

Think of it as two college friends moving a heavy television that weighs 200 lbs. Friend A can lift 75 lbs easily, but friend B (who works out at the gym every day and is a collegiate discus thrower) can lift 125 lbs. Neither friend can lift and move the television by himself, but together, sharing the load and combining their strength, they can lift 200 lbs. If either drops their side (or severs the bond), it will be a big problem! So by sharing their strength and unique characteristics, something not possible individually is achieved. This is how covalent bonding works.

Table 13.1 Ionic and covalently bonded compounds have opposite strengths and weaknesses.

Chemical Bonding Covalent Bonding

The bonds between two hydrogen atoms with one electron each is called a covalent bond.

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