Aim: How are coordinate covalent bonds different than regular covalent

bonds?

Do Now:1.Take out a calculator and reference tables.

2.Draw a dot diagram for the following molecules: •MgCl2

•H2O

•NH3

Answers to the do now

• MgCl2

• H2O

• NH3

What type of bond do those compounds have?

• MgCl2

• H2O

• NH3

• What happens to electrons in a covalent bond?• In a covalent bond, the atoms involved share

electrons. Example: H2O

A new type of bond…• Coordinate covalent bonds – a pair of shared

electrons is supplied by a single atom. • Example: The H+ ion is a particle that can accept a

pair of electrons (remember that H+ is basically a proton). It can join a water molecule to form H3O+ . This is called a hydronium ion. It can be written as shown above or H+

(aq) .

• Let’s draw the dot diagram.

Another Example

• NH3 – Let’s draw the dot diagram.

• If NH3 accepts a H+ what does it become?

• Let’s draw the dot diagram.

How can we tell which bond is the coordinate covalent bond?

• You can’t. Once the coordinate covalent bond is formed, it is indistinguishable from an ordinary covalent bond.

• What is the result? • Now, you have a polyatomic ion with a positive or

negative charge. • Most polyatomic ions contain coordinate covalent

bonds. • Where can we find a list? • Reference Table E

Activity

• Textbook page 400 – Copy and Answer Questions 18-24

Homework #