Covalent Bonding

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Transcript Covalent Bonding

Chemistry of Life
Chapter #2
ST 110
OBJECTIVES

Define Terms related to Chemical organization

Describe the structure of an atom


Compare and contrast ionic and covalent
bonding
Distinguish between organic and inorganic
compounds
OBJECTIVES

Discuss chemical characteristics of water

Explain the concept of pH

Discuss the structure and function of
organic molecules
Life is Chemistry

Food Digestion
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Formation of bone tissue
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Contraction of muscles
BIOCHEMISTRY
 Studying chemical aspects of life
Levels of Chemical Organization
 Matter
 Molecules
 Atoms
ATOMS
Composed of subatomic particles

Protons
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Electrons
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Neutrons
Atoms
 Nucleus
 Atomic number
 Atomic mass
Atoms
 Electrons stay in certain limits
called orbitals
Each orbital can hold two electrons
The closer to the nucleus, the lower
the energy level
Orbitals

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The second energy level has four orbitals
How many electrons can be held in the
second energy level?
IMPORTANCE????
The outer number of electrons
determines how the atom
“behaves chemically”
Elements
Element- pure substance of only one
type of atom
Each element has a symbol
Example: Hydrogen
Nitrogen
Potassium
C.O.H.N.
Four atoms that make up 96%
of the human body
Carbon
 Oxygen
 Hydrogen
 Nitrogen

Molecules and Compounds


Atoms unite with each other to form
molecules.
Compounds have more than one element
in them.
Compounds
The number of atoms in each molecule
is expressed by a subscript
Example: CO2 = carbon dioxide
one carbon, two oxygen's
H2O2 = hydrogen
peroxide
two hydrogen’s, two oxygen’s
Compounds/Chemical Bonding
Chemical bonds form to make atoms more
stable
 An atom is stable when it’s outer energy
level is full
Atoms react to each other to make their
outer most level full
Ionic Bonds
Electrons are
donated
One atom will become negatively charged,
and the other will become positively charged.
+++POSITIVE ION +++
• an ion that has given up its
electron to another atom
---NEGATIVE ION--• an ion that has borrowed
an electron
IONIC BONDS
Na-sodium – donates one electron
then becomes positive
Cl-chlorine- borrows one electron
then it becomes negative
Na + Cl = NaCl (sodium chloride)
IONS
 Ionic molecules dissolve easily in
water
Dissociate- when ionic bonds break
apart
 Electrolytes- are molecules that
form ions when
dissolved in water
QUESTION???????
What are the four main atoms that
make up 96% of the human body?
QUESTION????????
What is a positive ion?
What is a negative ion?
Covalent Bonds
 Covalent Bonds
Atoms can fill their energy level by
sharing electrons
 Covalent bonds do not break apart in water
Covalent Bonding
Question???
What is ionic bonding?
Question????
What is Covalent bonding?
Inorganic Chemistry
 Inorganic compounds do not contain
Carbon-Carbon , or Carbon Hydrogen
bonds
 Few inorganic compounds have carbon
in them
 Inorganic compounds are smaller and
less complex than organic compounds
H2O
Inorganic Compound
Why is water considered inorganic?
Is it a solvent, or a solute?
Solvent is a substance in which other
substances are dissolved.
Water is a Solvent !!!
Solute is a substance that dissolves into
another substance.
Salt is a solute!!!
Mixture- a blend of two or more
kinds of molecules
Aqueous solution - When water is
the solvent for two or more kinds
of molecules
Dehydration Synthesis
 Synthesis- Is the reaction in which
two reactants combine to
form a product
Dehydration synthesis can only occur
when a water molecule is removed
from the reactants and then they bind
to form a larger product.
Hydrolysis

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Water disrupts the bonds in large
molecules
The larger molecule is broken into smaller
molecules
Hydrolysis is the reverse of dehydration
synthesis
Chemical Reactions Always
Involve Energy Transfers
 Some energy is stored as
potential energy in the chemical
bonds
Ex: ATP (adenosine triphosphate)
pH Balanced !
Herbal Essence Shampoo?
or something else?
pH balance is 7
Which way does an ACID
go on the pH scale????
Which numbers on the pH
scale represent a base?
Acids are compounds that produce
an excess of H+ ions
Bases (alkaline) are compounds that
produce an excess of OH- ions (or
decreased in H+)
Isotopes

Isotopes- two atoms with the same
atomic number, but different atomic
mass
Metric System

1 meter= 39.37 inches

1 centimeter= 1/100 meter

1 millimeter= 1/1,000 meter

I micrometer= 1/1,000,000 meter
End of Day 1
Questions???
Organic Chemistry
 Much more complex than
inorganic compounds
Larger than inorganic compounds
Organic Chemistry
Four major types of organic compounds
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Carbohydrates
Lipids
Proteins
Nucleic Acids
Carbohydrates
Carbo-carbon
hydrate-water
 Basic unit of a carbohydrate is called
monosaccharide
EX: Glucose important monosaccharide
 Primary source of energy
Carbohydrates
 Disaccharide- a molecule made up
of 2 saccharide units (double sugar)
EX: Sucrose- table sugar
Lactose- milk sugar
• After eaten, the body digests them
to form monosaccharides to be used
as cellular fuel
Carbohydrates
 Polysaccharides- many saccharides joined
together
EX: glycogen and starch
 Each glycogen molecule is a chain of
glucose molecules joined together
 Liver cells and muscles cells form glycogen.
Excess glucose in blood is stored for later use.
Carbohydrates
 Carbohydrates have potential
energy stored in their bonds
Lipids
 Lipid- fat and oils
At room temperature
Fats- solid lipid
Oils- liquid lipid
Lipids
Triglycerides
• Bonds can be broken apart to yield
energy
• Store energy in cells for later use
Lipids
 Phospholipids
The phosphorus containing unit in
each molecule forms a head that
attracts water
Two fatty acid tails repel water
Cholesterol
 Performs several important functions
in the body
Combines with phospholipids in cell
membrane to stabilize bi-layer structure
 Body uses cholesterol to make steroid
hormones. Estrogen, testosterone,
cortisone
Proteins
 Very large molecule made of amino
acids
 Amino acids are held together by peptide
bonds
 Two types of proteins
Structural
Functional
Proteins
Structural Proteins
 Form Structures of the body
 Collagen- fibrous protein that holds many
tissues together
 Keratin- forms tough waterproof fibers in
outer layer of the skin
Proteins
Functional Proteins
 Participate in chemical processes
 Hormones, cell membrane channels
receptors, enzymes
Enzymes
 Catalysts- aid in chemical reactions
 Lock-and-key model
 Proteins can combine with other
organic molecules to form glycoproteins
lipoproteins
Nucleic Acid
DNA-deoxyribonucleic acid
• Master code
• Double helix
Nucleic Acid
RNA- ribonucleic acid
 Working copy
Nucleic Acid
 Made of nucleotide units
 Sugar (ribose, or deoxyribose)
 Phosphate- nitrogen based
adenine, thymine or uracil, guanine
cytosine
What are the four major types of
organic compounds found in the
body?
What is glycogen?
What is the primary source of
energy for cells?
What are lipids?
What are proteins made of?
What is an enzyme?
What are the two types of
nucleic acids?
What are the nitrogen bases?
What shape is DNA?
End of Day 2
Questions???