Transcript CHEMPPT

GOOD MORNING or
AFTERNOON!!
Basic Chemistry
Chapter 2
The Basics-Matter & Energy
• CHEMISTRY
– the science that explores changes in matter &
energy
• matter
– has mass (same as weight for our purposes)
– occupies space
– can exist in three “phases”
• solid
• liquid
• gas
The Basics-Matter & Energy…(cont’d)
• Thus we are matter!!!
• S-O-O-O-O-O
CHEMISTRY IS THE
STUDY OF US!!!
STRUCTURE OF MATTER
• 117 “basic kinds” of matter
• elements
– 92 naturally occurring (25 created in nuclear reactors)
• each is “pure matter
• basic building blocks from which everything is made
• atoms
– smallest unit (pieces) of elements
– interact during chemical reactions to form
compounds
• matter formed from two or more elements
• molecules smallest units of compounds
STRUCTURE OF AN ATOM
• subatomic particles
– protons
• in the nucleus
– center of the atom
• positively charged
• mass of “1” (AMU)
• ATOMIC NUMBER
ATOMIC STRUCTURE…(cont’d)
• neutrons
– have no electrical charge
– mass of “1” (AMU)
• AMU = “atomic mass unit”
– in the nucleus
– number may vary
• isotopes
– atoms of an element that differ in the number of
neutrons
ATOMIC STRUCTURE (cont’d)
• electrons
– negatively charged
– mass of “0”
– in energy shells, or orbits” surrounding
the nucleus
ATOMIC MASS
• mass of all protons + mass of all neutrons + mass of
all electrons
• (number of protons) (mass of 1 proton) + (number of
neutrons) (mass of 1 neutron) + (number of
electrons) (mass of 1 electron)
• ATOMIC NO. + NUMBER OF NEUTRONS = ATOMIC
MASS
• NUMBER OF NEUTRONS = ATOMIC MASS - ATOMIC
NUMBER
ELECTRON DISTRIBUTION
• modern theory recognizes e- in “clouds” or
energy levels
– The further from the nucleus, the more energy
e-’s have
• Bohr model has e-’s in 2-D orbits
– # varies with shell
• 2 in the first
• 8 in the second
• 8 in the third (sometimes 18)
– generally 8 is the most stable configuration
ELECTRON DISTRIBUTION…cont’d
All atoms “want” 8 electrons in their
outermost shells and will interact with
other atoms to the end that all reach 8.
Basis for formation of molecules
(compounds)
FORMATION OF MOLECULES
• atoms interact such that both (all) have 8 electrons
in outermost orbit
• thus, molecules are the most stable energy states for
atoms and their electrons
• attractions between atoms in a molecule are
chemical bonds
– attractions result from distributing electrons so that each
atom in the molecule has 8 in its outermost shell, at least
part of the time
TYPES OF CHEMICAL BONDS
• IONIC-one atom loses electrons, other gains
electrons
– atom that loses electrons has a net positive charge
• cation
– atom that gains electrons has a net negative charge
• anion
– unlike charges attract
• molecules form
• many elements in the body occur as ions
– called electrolytes
TYPES OF CHEMICAL BONDS…cont’d)
• COVALENT-two atoms share one or more
pairs of electrons
• each has 8 electrons in its outermost orbit
at least part of the time
– non-polar covalent bond
• atoms share electrons equally
– carbon tetrachloride
– methane
– polar covalent bond
• unequal sharing of electrons between atoms
– water
WATER
•
70% of human body
–
•
some tissues higher
functions in the body
1.
coolant
•
high specific heat
–
1.
solvent
•
–
–
can absorb heat w/o large increase in temperature
solute-molecule that dissolves
lubricant
enters reactions
TYPES OF CHEMICAL BONDS…cont’d)
• HYDROGEN bonds
– form between molecules not within molecules
– each weak
• many hydrogen bonds form very strong structures
• water as an example
CHEMICAL REACTIONS
• Necessary for cells to remain alive
• Atoms in reacting substances (reactants)
are rearranged to form different
substances (products)
• Each cell is a chemical factory
– growth, maintenance, repair, secretion,
contraction
• metabolism
Types of Chemical Reactions
DECOMPOSITION- AB -> A + B
– molecules broken into smaller molecules
•occurs in cells as well as outside them, e.g.
digestion in the small intestine
– hydrolysis
•decomposition involving water
– catabolism
•all the decomposition reactions in a cell
Types of Chemical Reactions
SYNTHESIS – A + B -> AB
– opposite of decomposition
– small molecules are “made” into large
molecules
– dehydration synthesis (condensation) is the
formation of a bond by the removal of water
•opposite of hydrolysis
– anabolism
•all the synthesis reactions in a cell
Types of Chemical Reactions
• REVERSIBLE
– if A + B -> AB, then AB -> A + B
– two reactions occurring simultaneously
•one decomposition, one synthesis
– at equilibrium, the rates of the two reactions
are balanced, i.e. as one molecule of AB is
produced, one is broken down
ACIDS AND BASES
• acids
– release H+ ions in solution
– produce solutions of pH’s less than 7
– minimum pH (most acidic solution) = 1
• bases (alkalis)
–
–
–
–
combine with hydrogen ions
release OH- ions in solution
produce solutions with pH’s greater than 7
maximum pH (most basic [alkaline] solution) =
14
pH SCALE
• measures degree of acidity or alkalinity of a
solution
• measures amount of hydrogen ions in a solution
• one in 10, 000,000 (107) water molecules ionizes to
produce a H+ and an OH - ion
• thus, numbers of hydrogen ions = numbers of
hydroxyl ions
– solution is neither acidic nor basic
– solution is neutral
– solution has a pH of 7
Some Bottom Line
Considerations
1. Life is carbon-based.
2. That is, to make the compounds of life,
we start with carbon atoms.
3. The major compounds of life are1.
2.
3.
4.
carbohydrates
lipids
proteins
nucleic acids
1.
Some Bottom Line
Considerations
…cont’d
To make carbohydrates we start with
carbon atoms and add hydrogen and
oxygen atoms.
2. To make lipids we start with carbon
atoms and add hydrogen, oxygen,
nitrogen, phophorous and sulfur
atoms
– albeit not all of them to carbon.
Some Bottom Line
Considerations…cont’d
1. To make proteins we start with
carbon atoms and add hydrogen,
oxygen, nitrogen and sulfur atoms.
2. To make nucleic acids we start with
carbon atoms and add hydrogen,
oxygen, nitrogen and phosphorous
atoms
– Albeit not all of them to carbon.
Carbon Skeletons & Functional Groups
• GENERAL REMARKS
– since carbon has four electrons in its outer shell it can
bond with four other atoms
– the bonds are covalent and hence quite strong
– usually carbon bonds with hydrogen, oxygen, nitrogen
or another carbon
– carbon atoms can share two electrons with another
carbon atom or with an oxygen atom
• double bond
General Remarks..cont’d
• carbon-carbon bonding makes possible long
chains containing as many as 50 or more carbon
atoms
– chains may contain one or more “internal” double
bonds
• carbon chains can form “rings” (cyclic
compounds)
– cyclic compounds may contain one or more “internal”
double bonds
– cyclic compounds may contain one or more atoms
other than carbon, e.g. oxygen or nitrogen
General Remarks..cont’d
• carbon chains make up the skeleton or backbone
of organic molecules
• functional groups can be attached to the carbon
chain, or the cyclic compound
– functional groups are clusters of certain atoms that
always behave in certain way (see Table 2.4 on page
44)
General Remarks..cont’d
• So, given these considerations about carbon
• And with the knowledge of “functional groups”
• We can look at ---
Carbon Skeletons & Functional Groups
• GENERAL REMARKS
– since carbon has four electrons in its outer shell it
can bond with four other atoms
– the bonds are covalent and hence quite strong
– usually carbon bonds with hydrogen, oxygen,
nitrogen or another carbon
– carbon atoms can share two electrons with another
carbon atom or with an oxygen atom
• double bond
General Remarks..cont’d
• carbon-carbon bonding makes possible long
chains containing as many as 50 or more carbon
atoms
– chains may contain one or more “internal” double
bonds
• carbon chains can form “rings” (cyclic compounds)
– cyclic compounds may contain one or more “internal”
double bonds
– cyclic compounds may contain one or more atoms other
than carbon, e.g. oxygen or nitrogen
General Remarks..cont’d
• carbon chains make up the skeleton or backbone of
organic molecules
• functional groups can be attached to the carbon
chain, or the cyclic compound
– functional groups are clusters of certain atoms that
always behave in certain way (see Figure 3.2, page 35)
• molecules composed of only carbon and hydrogen
are do NOT have a charged portion, hence do not
attract other molecules
– nonpolar
– hydrophobic (since they do not attract water)
General Remarks..cont’d
• carbon molecules contain functional groups may
have a charged portion
– polar molecules
– since they attract water they are said to be hydrophilic
(“water loving”)
MOLECULES OF LIFE
• organic molecules
– molecules containing carbon
– macromolecules (“large molecules)
• made of long chains of carbon compounds
• building blocks called monomers, I.e. “single
units”
• monomers may be bonded together into
polymers, i.e.“many units”
CARBOHYDRATES
• means “hydrated carbon”, i.e. carbon + water
– general formula = CH2O
– Made up of C,H and O
– simple carbohydrates are monomers
• called monosaccharides, or sugars
– 6 carbon monosaccharides (C6H12O6)
• called “hexoses”
• glucose, fructose, galactose
– 5 carbon monosaccharides (C5H10O5)
• ribose
• deoxyribose
Glucose
Fructose
• May look 5-sided, but it has 6-Carbons, so
it is a hexose sugar
Galactose
• It may look a lot like glucose, but there are
differences.
Glucose vs. Galactose
• Inquiring minds want to know ...
CARBOHYDRATES…cont’d
• complex carbohydrates
– dimers
– two monomers (C12H22O11)
• glucose + glucose = maltose
• glucose + fructose = sucrose
• glucose + galactose = lactose
– polymers (polysaccharides)
• starch
– polymer of glucose
» straight chain
– plants
– “amylose”
COMPLEX CARBOHYDRATES…cont’d
• glycogen
– polymer of glucose
– branched chain
– animals
• stored in muscles and liver
COMPLEX CARBOHYDRATES…(cont’d)
• cellulose
– plants
– dietary fiber
– straight chain
polymer of glucose
– provides structural
support
– Note the up/down
links at sharp angles
between glucose
molecules.
LIPIDS
• diverse in structure
• do not dissolve in water
• fats and oils
– known as triglycerides
TRIGLYCERIDES
• composed of only three elements
– C, H and O
• molecule of glycerol and three fatty acids
– glycerol is a 3 carbon compound containing only
C, H and O
– fatty acids
• long chains carbon and hydrogen with
• saturated or unsaturated
FATTY ACIDS
•
•
•
•
contain only C, H and O
saturated fats have saturated fatty acids
in animal fats
have hydrogen at every position along the
carbon chain
• no double bonds
FATTY ACIDS (cont’d)
• unsaturated fats have unsaturated fatty
acids
• in plant oils
• have one or more double bonds
SOAPS
• emulsifiers
– emulsification = to break up into smaller
globules
• not lipids but help to emulsify lipids
• bile emulsifies fats in the digestive tract
PHOSPHOLIPIDS
• polar heads
– negatively charged
• nonpolar tails
• similar to triglycerides except that a
phosphate group replaces one of the
fatty acids
• thus “elemental analysis” = C, H, O, P
STEROIDS
• made up of four fused carbon rings
• cholesterol is a precursor for many of
them
• sex hormones are steroids
– estrogen, progesterone, testosterone
PROTEINS
• polymers of amino acids(monomers)
• peptide bonds (covalent bonds) join amino
acids
• 20 different amino acids used to make all
proteins
• amino acids, hence proteins, contain only C,
H, O, N,
• S
– P found in small numbers of very specialized
nuclear proteins
PROTEINS (cont’d)
• serve a wide variety of functions in the
body
• proteins have levels of organization
– primary structure
• sequence of amino acids
PROTEIN STRUCTURE
(cont’d)
• secondary structure
– any twisting of the primary chain
• tertiary structure
– any folding of the twisted chain
• quaternary structure
– results when several polypeptides are
folded together
PROTEIN STRUCTURE
(cont’d)
• shape of a protein is important to its
function
• proteins can be denatured
– unfolded and rendered nonfunctional
TYPES OF PROTEINS
• two types of proteins exist
– globular proteins
• Enzymes and many non-enzyme molecules are
globular
– fibrous proteins
• have a rod-like shape
• a structural function, like myosin in
muscle
TYPES OF PROTEINS (cont’d)
• keratin
– a fibrous protein found in skin, nails, and
hair
• collagen and elastin
– fibrous proteins of tendons, ligaments,
bone, and cartilage
NUCLEIC ACIDS
• polymers of nucleotides
– 3 parts
• 5 carbon sugar
• N-containing base
• phosphate group
• nucleotides contain C, H, O, N, P
– hence the elemental analysis of nucleic acids is C,
H, O, N, & P
TYPES OF NUCLEIC ACIDS
• DNA
– two “chains” of nucleotide polymers
– genes
– carry coded information for cell blueprint
• RNA
– one “chain” of nucleotide polymers
– “decodes” DNA
– functions in protein synthesis
ATP
• adenosine triphosphate
• a carrier of energy
• our energy “currency”