What Are Chemical Bonds and Why Do They Form?

Comments (19)

What Are Chemical Bonds and Why Do They Form?

By: George V Grant

Attraction between atoms or ions leads to a chemical bond. According to the types of bonds contained in a molecule, the physical properties including melting point, hardness, electrical and thermal conductivity and solubility are determined. Chemical bonds involve only the outermost or valence electrons of atoms. Using the example of the simplest element, hydrogen, its two atoms on approaching each other, cause electon-electron and proton-proton repulsions to attempt separation of the atoms. But counterbalance by proton-electron attraction fuses the two hydrogen atoms forming a bond.

This example demonstrates the gain, loss and sharing of electrons by atoms for possession of the same number of electrons as the noble gas in closest proximity on the periodic table. With eight valence electrons (s2p6), all noble gases are chemically stable in a phenomenon called the octet rule. But certain exceptions are possible. Among them, one group of atoms has less than eight electrons like hydrogen with only one. BeH2 has just four valence electrons around Be, with Beryllium contributing two electrons and each hydrogen with one. The second exception applies in elements in periods 4 and above. Their atoms can have over four surrounding valence pairs in certain compounds.

Types of Chemical Bonds

Familiarity with three types of chemical bonds is required for the SAT II Chemistry exam, ionic bonds, covalent bonds and metallic bonds.

Ionic Bonds

An electrostatic attraction between ions with opposite charges, cations and anions causes ionic bonds. They usually involve metals and nonmetals as elements active in ionic bonds are mostly from opposite ends of the periodic table with an electronegativity difference exceeding 1.) 67.) Being very strong, ionic bonds in compounds increase melting points and take a solid form in normal conditions. Finally, an electron in an ionic bond is transferred from the less electronegative atom to the more electronegative element. A prime example of an ionic bond-content molecule is NaCl or table salt.

Covalent Bonds

Atoms may share electrons instead of transferring them from atom to atom, resulting in covalent bonds. But the sharing is rarely ever equal due to the difference in electronegativity value of each atom. The only exception is the bond between two atoms of the same element. Covalent bonds are said to be non-polar when the difference in electronegativity of two atoms ranges from 0 to 0.4.) Polar refers to electronegativity difference between 0.4 and 1.) 67.) For both non-polar and polar covalent bonds, higher electronegativity in an element results in stronger attraction of the electron pair. Carbon dioxide, CO2 molecules have two bonds which are covalent bonds.

It is possible for covalent bonds to be single, double or triple. A single bond occurs when only one pair of electrons is shared. This single bond is a sigma bond with the electron density being most pronounced along the line joining the two atoms.

Metallic Bonds

Metallic bonds are exclusive to metals alone, including aluminium, gold, copper and iron. Each atom in a metal shares a bond with a number of other metal atoms, thereby allowing their electrons unrestricted movement within the metal structure. It is this specific phenomenon that is behind the properties of metals being unique, an example being their high conductivity.

That basically sums up the essence of chemical bonds, the differences in various types and the reasons for molecular structures being formed.

About The Author

Dr. George Grant is an experienced researcher in Bio-chemistry. He has done extensive researches and experiments in the field. He is a visiting faculty for some of the most reputed Science colleges. For more information on Chemistry Tools and Definitions, please visit: http://www.chemicool.com.



Ariday? 24.12.2009. 06:46

How will chemical bonds form between metals and nonmetals? how will chemical bonds form between these elements, metal and nonmetal elements?

A. electrons are transferred to the nonmetal
B. electrons are transferred from the nonmetal
C. electrons are shared by the metal and nonmetal atoms
D. electrons move freely among the atoms of the compound


Admin 24.12.2009. 06:46

if you're talking about a metal and non-metal, it's gonna be A.

think about it this way, when you have two atoms, right, a metal and a nonmetal, what's gonna be more electronegative? the nonmetal. so the nonmetal really wants electrons. why, you ask? so it can be like a noble gas. the non-metal, too, wants to be like a noble gas, right? so it wants to lose electrons.

there's going to be an overlap between the metal and the nonmetal, but the nonmetal is going to take most of the electrons. the metal will be left with pretty much nothing, except it's still attracted.

when you have salt, NaCl, the Cl wants to gain an electron and the Na wants to lose it. Perfect situation. The Na gives the Cl an electron and is happy. Actually, both are happy. so in short (maybe long?), A.


solo 20.09.2009. 07:43

What type of chemical bond forms between atoms within a water molecule together? What type of chemical bond forms between water molecules, binding them to one another?


Admin 20.09.2009. 07:43

Covalent bonds within the molecule (i.e. H to O).

But different water molecules are held together by 'hydrogen bonding', whereby the relative positivity of the Hs in one water molecule is attracted to the relative negativity of the O in another molecule.


tomyRD 30.07.2011. 06:16

What is happening with the energy when a chemical bond is forming and breaking? What I read said that when a chemical bond is formed, energy is released, vice-versa.

But when it comes to anabolic reaction, it seems contradicting. When our body makes muscle or fat, it forms chemical bonds, right? Where is the energy that released from the bonding of muscle or fat? Can we use it? Doesn't it mean that we get double energy? One is from the stored energy in the form of muscle or fat, another is from the released energy of bond forming process.

I know this all sounds weird. But I would thank very much if someone explains these things thoroughly to me :)


Admin 30.07.2011. 06:16

Bonds contain Potential energy (the ability to do work) due to many factors: Electron position, natural shape, form, type of chemical in question, etc). Energy is con-severed, meaning you can't get "double energy". Energy is energy. it can be put in different forms (potential energy, kinetic energy,etc), but energy in itself can't be changed (energy: ability to do work)

When it comes to reaction, there are two types of reactions: exothermic (giving off heat reactions : reactants --> products + energy) and endothermic reactions (absorbing heat reactions: reactants + energy --> products). Note that reactants don't instantly become products. A series a complex steps happens between them that involves breaking, and reforming of different bonds before the FINAL products results.

" When a chemical bond is FORMED energy is released, v/v" , is actually what happens when "sufficient additional energy" is added to overcome what we call activated complex point. Energy is then released after the reaction. That new energy created (the ability to do work) is used to reform NEW bonds, the bonds you see in your net (start-finish) equation. At the end of all the reactions, there may be a TOTAL loss of energy or TOTAL gain in energy OF THE SURROUNDINGS.

It's hard to explain, I had the same question as you; I took an advanced bio course before I took the recommended pre-req chem courses. In time you'll understand chemical bonds :P

Hope this gives you something to chew on.


Meg 28.05.2012. 16:38

What chemical bonds are formed or broken within a hot pack? I believe this is an endothermic reaction...and why do the chemical bonds form or break?
I meant to write exothermic reaction....


Admin 28.05.2012. 16:38

The most common process that occurs in hot packs is crystallisation, and crystallisation of solids from a solution is a physical change rather than a chemical change.
The most common reusable hot packs contain a supersaturated solution of sodium acetate (NaCH3COO) in water. Crystallisation is triggered by flexing a small flat disc of notched ferrous metal embedded in the liquid. Pressing the disc releases very tiny adhered crystals of sodium acetate into the solution which then act as nucleation sites for the crystallisation of the sodium acetate into the hydrated salt (sodium acetate trihydrate). Because the liquid is supersaturated, this makes the solution crystallise suddenly, thereby releasing the energy of the crystal lattice.


mamu 11.01.2011. 02:02

How do you know what kind of chemical bonds they form? I am wondering how you know what kind of chemical bonds are formed by certain elements.


What kind of bond is CsBr?
- ionic
- metallic
- polar covalent
- non polor covalent
- network covalent

I'm so confused...


Jon101294 07.12.2010. 03:35

When a chemical bond is formed, the constituent atoms acquire the valence electron configuration of noble g? When a chemical bond is formed, the constituent atoms acquire the valence electron configuration of noble gases called__________________.


Admin 07.12.2010. 03:35



Cindy 26.01.2013. 05:37

What happens when two atoms form a chemical bond? What happens when two atoms form a chemical bond? A chemic? What happens when two atoms form a chemical bond?
A. A chemical bond forms when two atoms transfer or share outer electrons to complete their outer shells.
B. A chemical bond forms when two atoms transfer or share protons to achieve a stable nucleus.
C. Two atoms fuse together to form a chemical bond.


Admin 26.01.2013. 05:37

the answer is a.


Swishbig 06.03.2009. 03:07

How is a chemical bond formed? i want to know how a chemical bond is formed for my science test tomorrow, thank you!


Admin 06.03.2009. 03:07

There are three ways a chemical bond can form. The first type is a covalent bond, where two atoms need additional electrons to complete their outer shells so they share electrons with each other. The second type is an ionic bond. This happens when one atom has a stronger pull on the electrons, so electrons are transferred to that atom from the other. The third type is hydrogen bonds, which happens when two hydrogen atoms from different molecules or different parts of the molecule are attracted to each other due to differences in charge.


james saywer 13.10.2009. 02:34

when two or more elements are joined by chemical bonds to form a new pure substance, the substance is called w? when two or more elements are joined by chemical bonds to form a new pure substance, the substance is called what?

james saywer

Admin 13.10.2009. 02:34

A compound.

"A chemical compound (frequently shortened to compound) is a pure chemical substance consisting of two or more different chemical elements"



Lauren 01.09.2012. 21:11

How to know what chemical bond will be formed between 2 elements? An element ?X? has atomic number of 12 and another element ?Y? has an atomic number of ?16?.

1- What type of chemical bond can be formed between element X and Y?

2- One atom of element ?X? can chemically bond with how many atoms of element ?Y??

My teacher is wanting us to review some chemistry problems but its been so long, I cant remember how to do all of them. How do I go about solving these problems?

Thanks in advance!


Admin 01.09.2012. 21:11

#12, or Magnesium, is an Alkali-Earth Metal. #16, or Sulphur, is a Non-metal. Any bond between a metal and a non-metal is ionic.


Write a comment

* = required field





* Yes No