Chapter 5 Section 3

 In Ionic bonds, one atom gains valence electrons while the other loses valence electron(s) -- Transfer of Electrons Usually one atom is a metal and the other is a nonmetal. High Melting point Usually a solid at room temperature (crystali Conducts electricity in water

Ionic bonds are strong They transfer electrons Making + and - ions Metals and nonmetals get along Their melting point is high They conduct electricity – oh my Tiny crystals they will make Like pretty snowflakes

When non-metal atoms react together, they need to gain electrons to fill their outer shell and become stable. They can only do this if they share electrons with each other. The atoms share electrons so there is a force that joins the atoms together. This is called a covalent bond. H H incomplete outer shells H H both atoms have a full outer shell

Between 2 non metals Not as strong (require less energy to break) Low Melting point Often a gas or liquid at room temperature Do Not conduct electricity Share Electrons

Many elements exist as molecules – two or more atoms joined by a covalent bond. Each atom has a full outer electron shell and is therefore stable. Two common ways to indicate a covalent bond are: HH Cl dot diagram solid line HH – – HH O OCl

Fluorine has 7 valence electrons. It needs one more to be stable. F 2 or F – F F F There are two atoms in the molecule so it is called diatomic. To achieve this, it can shares an electron with another fluorine atom. This creates a single bond and the two fluorine atoms form a fluorine molecule.

O Oxygen needs 2 more electrons to have a completely full outer shell. O 2 or O=O To achieve this, it can share two electrons with another oxygen atom. This creates a double bond. O O O

Nitrogen needs 3 more electrons to have a completely full outer shell. N 2 or N ≡ N It can share three electrons with another nitrogen atom to do this. This creates a triple bond. N N N N

are usually insoluble in water but soluble in other solvents such as petrol; cannot conduct electricity – there are no free electrons to carry an electrical charge. In addition, molecular solids: have low melting and boiling points; are usually soft and brittle – they shatter when hit. The weak forces of attraction between molecules in molecular solids only require a small amount of energy to be broken. This means that molecular solids:

 When electrons are shared equally, this is known as a nonpolar bond.  Examples:

 Some atoms pull more strongly on shared electrons. This causes them to have slight electrical charges.  Known as Polar Bonds  Example: Water

Watch Ionic and Covalent Bonds being made Video Illustration of Ionic and Covalent Bonding

Covalent bonds are like brothers Their atoms are alike They share electrons with each other Making molecules – that’s right!

Ionic bonds are strong They transfer electrons Making + and - ions Metals and nonmetals get along Their melting point is high Conduct electricity – oh my Tiny crystals they will make Like pretty snowflakes

 What is a covalent bond?  How is it different from an ionic bond?  What type of bond would two oxygen atoms have?  If electrons are shared unequally, it is called a ____________?  What is an example of a polar bond? Nonpolar bond?

 Study Guide