
Covalent bond

Reactants

Products

Valence level

Octet rule

HONC

Reactivity

Chemical bond

Stable/unreactive

Unstable/reactive

Charge

Chemical equation

Law of conservation of matter


Atoms in compounds are held together by chemical bonds

Making bonds involves the electrons that surround each nucleus

Electrons that are available to form bonds are called valence electrons


Electrons of an atom are spread out in different layers around the nucleus to make an “electron cloud”

Layers are called energy levels

2 electrons go in the first energy level

8 electrons can go in the second energy level and beyond (octet rule)


If there are not 8 electrons for the outer level, these empty spots are called vacancies and some electrons are unpaired

Unpaired electrons in the outer layer are the valence electrons

Valence electrons can pair with those from other atoms to “fill” the vacancy

Creates a molecule

Bohr Model: shows all of the electrons in their energy levels
Lewis Dot Structure: shows just the valence electrons in the outer energy level


Reactivity of an atom is determined by the number of vacancies in its outer energy level

If there are vacancies, the atom is reactive/unstable

If there are no vacancies, the atom is nonreactive/stable

If the vacancies are filled due to bonding, the molecule is stable

1. ionic bonds
2. covalent bonds

There are other types of bonds and interactions but they are not as strong


Formed when one or more electrons are transferred from one atom to another

Atom that loses electrons becomes positively charged

Atom that gains electrons has a negative charge

These positively and negatively charged atoms are known as ions

These oppositely charged ions have a strong attraction for each other, forming an ionic bond


Electrons are shared by atoms instead of transferred

Moving electrons travel about the nuclei of both atoms, forming a covalent bond.


Single Covalent Bond: atoms share 2 electrons (1 pair)

Double Covalent Bond: atoms share 4 electrons (2 pairs)

Triple Covalent Bond: atoms share 6 electrons (3 pairs)


Bonds between the most important biological atoms will be covalent

Number of bonds each can make is important for the compounds that will be created using these atoms
This is the number of bonds each of these can form!
H O N C
1 2 3 4
Hydrogen -can form 1 bond
Oxygen- can form 2 bonds
Nitrogen- can form 3 bonds
Carbon- can form 4 bonds


Ionic vs. Covalent Video Quiz


Chemical Reactions: process that changes or transforms one set of chemicals into another set of chemicals

Involves changes to the chemical bonds that join atoms in compounds

Reactants: elements or compounds that enter into a chemical reaction

Products: elements or compounds produced by a chemical reaction

HINT: Reactants react to produce products!

Bonds of the reactants are broken and new bonds form in the products

6O
2
What process is this equation for?
Cellular
Respiration

Chemical Equation: a mathematical representation of a chemical reaction

Shows the numbers and types of compounds involved
+ C
6
H
12
O
6
 6CO
2
+ 6H
2
Reactants Products


The Law of Conservation of
Matter: matter (atoms and elements) in a chemical reaction cannot be created or destroyed

Only the arrangement of the atoms is changed, NOT the number or types

Both sides of a chemical equation must be
“balanced” (have the same number of atoms)

Are these equations balanced?
C + 2H
2
--> CH
4
Na
2
SO
4
+ CaCl
2
--> CaSO
4
+ NaCl
C
2
H
6
+ O
2
--> CO
2
+ H
2
O
2Al
2
O
3
--> 4Al + 3O
2
Yes
No
No
Yes