activity #4: chemical bonds. covalent bond reactants products valence level octet rule honc ...

Activity #4: Chemical Bonds

Covalent bond Reactants Products Valence level Octet rule HONC Reactivity

Chemical bond Stable/unreactive Unstable/reactive Charge Chemical equation Law of

conservation of matter

Vocabulary

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

Chemical Bonds

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)

Valence Electrons

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

Valence Electrons

Bohr Model vs. Lewis Dot Structure

Bohr Model: shows all of the electrons in their energy levels

Lewis Dot Structure: shows just the valence electrons in the outer energy level

Practice

Element Bohr Lewis DotCarbon

Nitrogen       

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

Reactive vs. Stable

1. ionic bonds 2. covalent bonds There are other types of bonds and

interactions but they are not as strong

Types of Chemical Bonds

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

Ionic Bonds

Electrons are shared by atoms instead of transferred

Moving electrons travel about the nuclei of both atoms, forming a covalent bond.

Covalent Bonds

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)

A covalent bond can be a…

HONC

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

H O N C1 2 3 4

Hydrogen -can form 1 bondOxygen- can form 2 bonds Nitrogen- can form 3 bondsCarbon- can form 4 bonds

This is the number of bonds each of these can form!

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

Chemical Reactions

Chemical Equation: a mathematical representation of a chemical reaction Shows the numbers and types of compounds

involved

Chemical Equations

6O2 + C6H12O6 6CO2 + 6H2O + ___

What process is this equation for?

Cellular Respiration

Reactants Products

ATP

Balancing Chemical Equations

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)

 C + 2H2 --> CH4

Na2SO4 + CaCl2 --> CaSO4 + NaCl

C2H6 + O2 --> CO2 + H2O   

2Al2O3 --> 4Al + 3O2

Practice

Yes

Yes

No

No

Are these equations balanced?