1. Introduction to Chemical Bonding
Miss Elaine Macalinao
Chemistry

2. Why form chemical bonds? Decrease potential energy Increase stability
Chemical bond: a mutual electrical attraction between the nuclei and valence electrons of different atoms that binds the atom together
Why form chemical bonds?
Decrease potential energy
Increase stability
All atoms trying to achieve a stable octet
Atoms unstable alone and lead more stable, happier lives when joined/bonded together with one or more other atoms
Octet recall noble gases stability? ns2np6

3. Types of chemical bonding
When atoms bond, their valence electrons are moved around in ways that make the atoms more stable
The way their valence electrons move around determine the type of bond that happens
3 major types of chemical bonds:
Ionic
Covalent
Metallic

4. Ionic Bonding
Ionic bond: chemical bonding that results from the electrical attraction between large numbers of cations and anions
Electrons are either gained or lost by an atom
In doing so, both atoms often achieve the electron configuration of the nearest noble gas
Occurs between metals losing electrons to nonmetals
Very strong bond
Other words: chemical bond in which one atoms loses an electron to form a positive ion and the other gains an electron to form a negative ion
TRANSFER OF ELECTRONS!
Ionic compounds = made up of atoms!

5. Ionic compound: composed of positive and negative ions that are combined so that the numbers of positive and negative charges are equal
Most ionic compounds exist as crystalline solids
3D network of positive and negative ions mutually attracted to one another
Ex: rocks, minerals

6. IONIC
Definition
Chemical bonding that results from the electrical attraction between large numbers of cations and anions
Types of atoms involved
Metals & nonmetals
Method of bond formation
Transfer of electrons
Type of structure
Crystal lattice
Physical state
Solid
Melting point
High
Solubility in water
Yes
Electrical conductivity
Other properties --
Image

7. Covalent Bonding
Covalent bond: chemical bonding that results from the sharing of electron pairs between two atoms
Neither atom has an electrical charge
Forces between atoms are weak
Bonding between atoms of the same elements is completely covalent

8. Molecule: a neutral group of atoms that are held together by covalent bonds
Molecular compound: a chemical compound whose simplest units are molecules
Diatomic molecule: a molecule containing only two atoms

9. COVALENT
Definition
Chemical bonding that results from the sharing of electron pairs between atoms
Types of atoms involved
Nonmetals
Method of bond formation
Sharing of electrons
Type of structure
Molecules
Physical state
Liquid or gas
Melting point
Low
Solubility in water
Usually not
Electrical conductivity No
Other properties
Odorous
Image

10. Metallic Bonding
Metallic bonding: the chemical bonding that results from the attraction between metal atoms and the surrounding sea of electrons
Within metals, vacant orbitals allow the atoms’ outer energy levels to overlap
Result = electrons become delocalized
Delocalized: not belonging to any one atom, but freely move about the metal’s network of empty atomic orbitals

11. De-excitation responsible for the shiny appearance of metal surfaces
Metallic Properties
High electrical and heat conductivity due to the freedom of electrons to move in a network of metals
De-excitation responsible for the shiny appearance of metal surfaces
- When light shines on these electrons, they vibrate and instead of energy springing from atom to atom it is reflected as visible light

12. Two important properties related to characteristics of metals:
Malleability: the ability of a substance to be hammered or beaten into thin sheets
Ductility: ability of a substance to be drawn, pulled, or extruded through a small opening to produce a wire
Characteristics possible because metallic bonding is the same in all directions throughout the solid

13. METALLIC
Definition
Chemical bonding that results from the attraction between metal atoms and the surrounding sea of electrons
Types of atoms involved
Metals
Method of bond formation
Electrons are delocalized among metal atoms
Type of structure
“Sea of electrons”
Physical state
Solid
Melting point
Very high
Solubility in water
Yes
Electrical conductivity
Other properties
Malleable, ductile, lustrous
Image

14. Bond Polarity
Most bonds are a blend of ionic and covalent characteristics
Difference in electronegativity determines the bond type
A large difference in electronegativity in a bond will result in ionic bonding
A small difference between two atoms will results in covalent bonding

15. Non-polar covalent bond: a covalent bond in which the bonding electrons are shared equally by the bonded atoms, resulting in a balanced distribution of electrical charge
Polar-covalent bond: a covalent bond in which the bonded atoms have an unequal attraction for shared electrons

16. Electronegativity Difference
Bonding type
How it looks like
0.0 – 0.3
Non-polar covalent
0.4 – 1.9
Polar covalent
2.0 – 3.3
Ionic
Recall: Differences in electronegativities reflect the character of bonding between elements

17. Chemical Bonding Video

18. Show your understanding!
Choose one of the following products to demonstrate what you have learned:
Story – choose one type of bonding and write “A Day in the Life of an Atom” story describing your chosen bond type. The story should incorporate at least 5 properties from your Bonding Chart
Comic Strip – Create a comic strip with 3+ frame for each bonding type. The comic should incorporate at least 3 properties from your Bonding Chart.
Single-Frame Cartoon- Draw a single-frame cartoon for each type of bonding. Each cartoon should incorporate at least 2 key properties from your Bonding Chart.
Essay – write a 5-paragraph essay comparing and contrasting each bonding type. The essay should incorporate the major properties from the Bonding Chart.