1. Bonding

2. What is it? A bond is the attractive force that holds atoms together
Usually only forms between atoms of different elements
It is the force that holds diatomic atoms together
Diatomic atoms are always found in pairs
Diatomic atoms I, Br, Cl, F, O, N and H
Bonds are formed and broken in chemical reactions

3. What are ions? Ions are particles with a charge
Atoms that have gained or lost electrons
Atoms gain electrons become negatively charged
They are called anions
Atoms that lose electrons become positively charge
They are called cations

4. Ionic Bonds
Ionic bonds are formed by the attractive force between oppositely charged ions
Formed by a metal and a non-metal
Electrons are transferred from one atom to the next
pi/NSC/5-bonds.htm

5. Characteristics of Ionic compounds Know all of these
Compounds formed by ionic bonds have these characteristics
High melting point
Soluble in water
Conducts electricity when in solution
Forms crystals

6. Covalent Bonding
Covalent bonds are formed when atoms share electrons to satisfy the octet rule
Sharing is not always equal – electrons may spend more time around one atom in the bond compared to the other atom

7. Polar Covalent Bonding
A type of covalent bonding when there is unequal sharing of electrons
One atom has a stronger attraction for the electrons than the other
These molecules have area of negative charge and an area of positive charge
Characteristics of polar covalent bonding
Soluble in water
Medium melting point
Do not conduct electricity when dissolved in water

8. Polar Covalent
The electrons spend more time around the oxygen, creating a partial charge
The hydrogens have a slight positive charge

9. Non-polar covalent bonding
A type of covalent bonding when the electrons are shared equally
The atoms have an equal attraction to the electrons
The molecules have no areas of charge
Characteristics of non-polar covalent substances
Low melting point
Low solubility in water
Does not conduct electricity in water

10. Electronegativity
Electronegativity is the tendency for atom to attract a bonding pair of electrons
It is measured on the Pauli scale
Fluorine has the highest attraction and given a value of 4.0
Francium is the lowest with a value of .7

11. Trends in electronegativity

12. How to determine the type of bond
The difference between the electronegativity of the two atoms in a bond will determine the type of bond
Difference
Bond type
Diff.<.4
Non-polar covalent
.4< Diff. <2.0
Polar Covalent
2.0 < Diff.
Ionic

13. Metallic Bonds Metallic bonds hold atoms of the same metal together.
The electrons flow between atoms
All the atoms in a metallic bond share all the electrons so they are free to move about throughout the metallic structure

14. Van der waals forces
Van der waals forces are an intermolecular attraction – two molecules are held together
The differing charged parts of covalent molecules are attracted to each other
The forces that keep molecules of the same substances together

15. H bonding
When the positive charge on a bonded H atom attracts to the negative part of a different molecule
Most often seen in water
Hydrogen bonds gives proteins their shape