20.2 Types of bonds

Warm up

What is a chemical bond?

How do elements seek stability?

Objectives Describe ionic bonds and covalent

bondsIdentify the particles produced by

ionic bonding and by covalent bonding

Distinguish between a non-polar covalent and a polar covalent bond

Introduction Represent by drawing the way that Na and Cl form

Nacl.Represent by drawing the way H and O form H2O

Gain or loss electrons

Atoms and ionsAn atom that has lost or gained electrons is called

an ion.An ion is a charged particle that has either fewer

or more electrons than protons.

Group Outer e-

Lose or gain

Charge of ion

Atoms 1 1 Lose 1 +12 2 Lose 2 +213 3 Lose 3 +315 5 Gain 3 -316 6 gain2 -217 7 gain1 -1

Monoatomic and polyatomic ions

Ions can be two types:1- monoatomic ions (1 atom ion)2- polyatomic ions (more than one atom ion)

Polyatomic ion

What type of ion each of the following atoms will form?

1- potassium K (19)2- Magnesium Mg (12)3- Aluminum Al (13)4- Fluorine F (9)

A bond forms

Ionic bondWhat happens when you put Mg and Cl together

and allow them to react?Will they form a bond?How do you think they will form a bond? Can you draw an illustration that shows how a

bond is formed, if Mg (z=12) and Cl (z=17).What is the charge of the compound formed?

Think and concludeCan you predict what type of ion is formed when

one atom loses electron and the other gains electron?

Predict what type of elements lose electrons and what type of elements gain electrons?

When is an ionic bond formed?

Covalent bondsHow do elements reach stability if they don’t lose

or gain?Do they form ions?Predict how water molecules are formed.

Types of covalent bondsDraw the structure of:1- water2- carbon dioxide3- nitrogen gas

Three types of covalent bonds1- single covalent bond (2 electrons are shared between 2 atoms)2- double covalent bond (4 electrons are shared between 2 atoms)3- triple covalent bond (6 electrons are shared between 2 atoms)Give example about a molecule which contains single covalent bond, another molecule with a double covalent bond and a third molecule with a triple covalent bond.

Ionic bond VS covalent bondCompare between ionic and covalent bonds.

Unusual sharingElectrons are not always equally shared between

atoms in a covalent bond.The strength of the atom is related to the size of

the atom, charge of the nucleus, and the total number of electrons an atom contains

Equally or unequally sharingAtoms on the right side of the periodic table tend

to attract electrons more

Polar or non-polar moleculeIf atoms of a molecule share electrons equally: the molecule is non-polar

Ex: Cl2, O2, CO2

If atoms of a molecule share electrons unequally:

The molecule is polarEx: H2O, HCl, CHCl3, HF

Wrap up

Assignments

Section review questions. Page: 614