Download ch02

Introductory Chemistry 2
Unit 2
Chapter 2
Chemical Elements
•
•
•
•
2
Fundamental unit in chemistry
Cannot be broken down by chemical
means
112 elements total
Use 1-2 letter symbols for each
•
•
•
26 normally present in your body
4 major ones & 8 others significant
(see table 2.1)
Unit 2
e.g. C= carbon, Na = sodium, Cl = chorine.
Atoms
•
•
•
•
2
Lowest unit of an element
Nucleus-protons (+), neutrons (0)
Surrounded by Electrons (-)
Total charge is neutral-
•
•
Proton number=atomic numberdefines element
Unit 2
Protons # = electron #
•
•
•
•
Atoms interact in characteristic
ways
Describing this is chemistry
When two or more atoms are held
together with chemical bonds the
result is a molecule.
Described by the molecular formula
2
Unit 2
Ions, Molecules & Compounds
Molecular Formula
•
2
Example: O2 = oxygen the gas
molecule has 2 atoms of oxygen bound together
•
H2O = water
•
•
Subscript = # of atoms of element
Connected letters & numbers =
molecule
Unit 2
Molecule has 2 atoms of H (hydrogen) and 1
atom of O (oxygen)
Figure 2.3
•
•
•
•
attraction between atoms to form
attachments = molecules
Electrons grouped into shells
preferred number in outer shell
leads to chemical activity
Can be covalent, ionic, polar
covalent and Hydrogen bonds
2
Unit 2
Bonding
Ionic Bonds
•
2
Can donate or accept electrons
from another atom ->
•
•
Opposite charges attract =>
bonding
Ionic bonding
Unit 2
Ions = atoms with a charge
Figure 2.4
Figure 2.4
Covalent Bonds
•
2
Can share electrons in outer shell > covalent bonds
e.g. water, many organic compounds
unequal sharing -> polar bond
some partial charges on the molecule
Unit 2
•
Figure 2.5a
Figure 2.5b
Figure 2.5c
Figure 2.5d
Figure 2.5e
Chemical Reactions- Synthesis
Putting atoms together
A + B => AB
Eg. 2H2 + O2 => 2 H2O
Synthesis in the body = Anabolism
Unit 2
•
•
•
•
2
Chemical ReactionsDecomposition
Splitting Molecules apart
AB => A + B
Eg. CH4 => C + 2H2
Decomposition in the body =
Catabolism
Unit 2
•
•
•
•
2
Other Reactions
2
• Exchange reactions
•
both decomposition & synthesis
E. g.
AB + CD => AD + BC
E. g.
AB <=> A + B
Unit 2
• Reversible reactions
• Go both directions
•
•
•
•
•
•
Good solvent for some molecules
Dissolve = Hydrophilic molecules
Don’t dissolve = Hydrophobic
molecules
Participates in chemical reactions
Absorbs & releases heat slowly
Needs large amount of heat to
evaporate
2
Unit 2
Nature of Water
•
•
•
Acid dissolves => H+ (1 or more)
Base dissolves => OH- ( 1 or more)
Acid plus base react => salt
•
E.g. HCL + KOH => KCL + H2O
acid base
salt
2
Unit 2
Acid, Base & Salts
pH Concept
•
•
•
•
The concentration of H+ or OHexpressed on the pH scale
0-14
At pH = 7.0: H+conc. = OH- conc.
Less than 7.0 = more H+ (acid)
The smaller the number, the more H+
More than 7.0 = more OH-
(alkaline)
The larger the number, the more OH-
Unit 2
•
2
Organic Compounds
Carbohydrates
Lipids
Proteins
Nucleic acids
Unit 2
•
•
•
•
2
Carbohydrates
•
Simple sugars = Monosaccharide
Major one in body = glucose
Disaccharides= 2- simple sugars
bonded
Formed by dehydration synthesis
E.g. glucose + fructose => sucrose
glucose + galactose => lactose
Glucose + glucose => maltose
Unit 2
•
•
•
2
Figure 2.8
Polysacchharides
•
2
Many sugars bonded in chains
Can have branching structures not usually
soluble in water
•
Glycogen- animal carbohydrate
Polyglucose
Starch- plant carbohydrate
Polyglucose
•
Cellulose- plant polymer
Polyglucose but indigestible = fiber
Unit 2
•
Figure 2.9
•
•
•
•
•
•
•
Insoluble in water = hydrophobic
Triglycerides
Phospholipids
Cholesterol
Steroids
Fatty acids
Fat soluble vitamins
2
Unit 2
Lipids
Figure 2.10
Figure 2.11
Figure 2.12
Cholesterol
Ring structures
Used to make steroid hormones
Help make membranes stiff
Made in liver
Unit 2
•
•
•
•
2
Proteins
Structural elements in cells
Chemical catalysts
Hormones
Antibodies
Polymers of amino acids
Unit 2
•
•
•
•
•
2
Amino Acid
Amino group
Carboxyl group
Side chain
~20 different side chains
A large variety of structures
Unit 2
•
•
•
•
•
2
Figure 2.13
Terminology
•
•
•
Amino acids joined by peptide
bond
2 = dipeptide, 3= tripeptide
Many =polypeptide
Functional polypeptide = protein
Includes structure up to quaternary.
Thus a protein may have 1 or more polypeptide
chains
Unit 2
•
2
Enzymes
•
•
•
Proteins serving as chemical
catalysts
Highly specific
Efficient
May be controlled
Unit 2
•
2
Figure 2.14
Nucleic Acids
•
Polymer of nucleotides =>
Phosphate
Sugar –pentose (ribose,
deoxyribose)
Base- 5 of them (4 per nucleic acid)
Adenine (A), guanine (G), thymine (T), cytidine
(C), uracil (U)
Unit 2
•
•
•
2
•
•
•
•
•
Deoxyribose & A,T,G,C
Bases pair: A-T & G-C
Two polymers hydrogen bonded
together
forms a double helix
Stores genetic information on
protein sequences.
2
Unit 2
DNA
Figure 2.15
RNA
Ribose & A,U,G,C
Single chain
Functions in protein synthesis
Required to translate DNA to
protein
Unit 2
•
•
•
•
2
ATP
•
Specialized for energy transport in
the cell
Carries energy in the chemical
bond between phosphate groups.
Unit 2
•
2
Figure 2.16