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