Why do Atoms form Bonds - Sierra Vista Chemistry

1 of 6 Boardworks Ltd 2009 What are bonds? Elements are the simplest substances that exist on Earth. Each element is made up of just one type of atom, usually joined to other atoms of the same element by bonds. This forms molecules such as chlorine (Cl2). Compounds are formed when different elements chemically react and form bonds with each other. Some compounds, like water (H20), have small, simple structures with

just a few atoms bonded together. Others compounds, like DNA, have large, complex structures containing thousands or even millions of bonded atoms. 2 of 6 Boardworks Ltd 2009 Why do atoms form bonds? Bonds involve the electrons in the outer shells of atoms. Each shell has a maximum number of electrons that it can hold. Electrons fill the shells nearest the nucleus first. 1st shell holds a maximum

of 2 electrons 2nd shell holds a maximum of 8 electrons 3rd shell holds a maximum of 8 electrons Filled electron shells are very stable. 3 of 6 Boardworks Ltd 2009 Why do atoms form bonds? The atoms of noble gases have completely full outer shells,

and so are stable. This makes the noble gases very unreactive, and so they do not usually form bonds. The atoms of other elements have incomplete outer electron shells, and so are unstable. By forming bonds, the atoms of these elements are able to fill outer shells and become stable. 4 of 6 Boardworks Ltd 2009

What are the types of bonding? Different types of bonds are formed depending on the types of atoms involved: ionic bonding occurs between metal and nonmetal atoms. covalent bonding occurs between nonmetals atoms only. metallic bonding occurs between metal atoms only. All bonds involve electrons and all bonding involves changes to the number of electrons in the outer shells of atoms.

How do you think electrons are involved in ionic bonding? 5 of 6 Boardworks Ltd 2009 What happens when atoms bond? 6 of 6 Boardworks Ltd 2009