Transcript Ch. 2 H. Bio Notes

Chapter 2
Chemistry!
MATTER!
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Everything around you is made of matter.
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Matter is anything that has mass and
occupies space.

What’s mass again?
Composition of Matter
Elements are one of the simplest
chemical substances…can’t break
down!
 90 occur naturally on Earth
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25 essential to organisms
 C,
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H, O, N…
Trace elements-present in small
amounts
 Iron
(Fe), Magnesium (Mg), Zinc (Zn)
Periodic Table
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Elements are arranged in the periodic
table according to physical and chemical
characteristics
Atoms: Building Blocks
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Atoms are the smallest particles of
elements that have that element’s
characteristics
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Review of Atomic Structure
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Nucleus-
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Protons- (p+)
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Neutrons- (n0)
Electrons and Energy Levels
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Electrons form a cloud around nucleus
Travel in specific regions called energy
levels.
Levels have limited capacities:
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Level 1-Hold max. of 2 eLevel 2-Hold max. of 8 eLevel 3-Hold max. of 18 e-
Elements are stable when outer level is full
Bohr Energy Level Diagrams
Isotopes of Elements
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Isotopes are atoms of the same
element that have different numbers
of neutrons.
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Most Carbon contain 6 neutrons….
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Others have 7 and 8…they are isotopes of the
element carbon
Referred to as C-12, C-13 and C-14
Some are unstable-used for radiation
therapy
Interactions of Matter
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A compound is a substance that is
composed of atoms of different elements
chemically combined.
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Chemical reactions happen when atoms
are rearranged and new bonds are formed
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Compounds important to us??
Bonding
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Covalent Bond- two atoms sharing
electrons to hold together
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Hydrogen Stability
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Molecules are groups of atoms held
together by covalent bonds with no charge
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Molecules are the simplest form of a
substance that retains its properties freely
Water Molecule
Ionic Bonds
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An atom that gains or loses electrons has
an electrical charge and is called an ion.
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Elements will give up/take electrons to fill
outer shells
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The attractive force between two opposite
charged ions is an ionic bond.
Ionic Bonds
Section 2.2- ENERGY
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Energy is defined as the ability to do work
or cause change.
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Free Energy is the NRG in a system
available for work.
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NRG can be in various forms and can transfer
forms.
In cells, it’s the NRG to fuel cell processes
NRG can also change states of matter….
States of Matter
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Atoms in a substance are actually in
constant motion.
The rate at which atoms or molecules
move determines the state.
Three Major States
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SOLIDS:
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LIQUIDS:
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DEFINITE VOLUME
DEFINITE SHAPE
DEFINITE VOLUME
NO DEFINITE SHAPE (Containers’ shape)
GASES:
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NO DEFINITE VOLUME
NO DEFINITE SHAPE
NRG & Chemical Reactions
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Metabolism is all of the chemical reactions
occurring within an organism.
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Reactions break down/build up molecules
important to function.
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Written in chemical equations using
symbols and formulas.
What process is this?
Breakdown of RXNs
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Reactants are on the left side of the
equation.
Products are on the right side of the
equation.
Reactant bonds are broken, atoms are
rearranged, and new bonds form to make
products!!
Coefficients vs Subscripts
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Coefficients- Big numbers before an
element or compound.
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Tell you how many molecules you have!
Ex.- 6CO2 means six molecules of CO2
Subscripts- Small numbers after an
element.
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Tell you how many atoms you have!
Ex. – H2O means 2 atoms of H.
NRG TRANSFER
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Chemical reactions that involve a net
release of NRG are known as exergonic.
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Chemical reactions that involve a net
absorption of NRG are known as
endergonic.
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Catalysts speed up reactions by lowering
the activation NRG, or NRG needed to
start the reaction.
Role of Catalyst:
Mixtures vs Solutions
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A mixture is a combination of substances
in which they retain their own properties.
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Sand & Water
Solutions are mixtures in which one or
more substances distribute evenly in
another substance
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Kool-Aid!!
Solutions
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Solutes are the substances dissolved in
solutions.
Solvents are the substances in which the
solute is dissolved.
Concentration is determined by the
amount of solute dissolved in a fixed
amount of solution.
If no more solute can be dissolved, the
solution becomes saturated.
Acids and Bases
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Water molecules can be broken down into
two oppositely charged ions in a process
called dissociation.
Acid vs Base
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pH measures how acidic or alkaline
(basic) a solution is.
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Acid is any substance that has more
hydronium ions (H3O+) in water. pH<7
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Base is any substance that has more
hydroxide ions (OH-) in water. pH>7
Acid/Base Characteristics
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ACIDS:
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Sour Taste
Can be corrosive
Examples:
BASES:
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Bitter Taste
Feel slippery
Examples:
Strength of Acids/Bases
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Strength is based on distance from
neutral, or pH of 7.
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Ex. #1- A base with a pH of 13 is stronger
than a base with pH of 8.
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Ex. #2- An acid with a pH of 1 is stronger
than an acid with a pH of 5.
pH Scale
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pH Scale is based on logarithmic scale.
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Change in unit equals ten times the
change in alkalinity or acidity.
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Ex.- pH 2 is ten times stronger than pH 3.
pH Scale
BUFFERS!!
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Living organisms are very sensitive to pH
changes.
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pH in organisms is controlled by buffers
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Buffers can neutralize small amounts of
acids or bases in a solution
APE MAN!!
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ATOMIC # = # Protons = # Electrons
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Ex- Boron has atomic # 5
Boron has 5 protons and 5 electrons!!
MORE APE MAN!!
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MASS # - ATOMIC # = # Neutrons
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Ex.- Cobalt has:
Mass # = 59
Atomic # = 27
59 – 27 = 32 Neutrons!
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Water’s Uniqueness
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1. Water is polar-it has an unequal
distribution of charge.
 Two Hydrogens=Positive End
 Oxygen=Negative End
Molecules attract to each other and to
ions
 Ability to dissolve other polar
substances…
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Hydrogen Bonding
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2. Hydrogen Bonding-the attraction of
opposite charges of H and O.
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Important for holding together large
molecules: Proteins!
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Also can occur between hydrogen and
most electronegative atom in another
polar molecule!
Hydrogen Bonds
Cohesion
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3. Cohesion is the attraction between
particles of the same substance.
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Creates high surface tension
 Floating organisms
 Beading on leaves
How’d he do that?
Adhesion
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4. Adhesion is the attraction between two
different substances.
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Allows water to creep up thin tubes:
capillary action
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Plants getting water from ground
Specific Heat/Vaporization
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5. Water has a high specific heat.
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Also has high heat of vaporization.
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Amount of heat NRG needed to raise/lower
1g of a substance by 1 degree Celsius.
Takes a lot to go from 0 (freezing) to 100
(boiling)!
NRG needed to convert 1g of a liquid to gas!
Water resists temperature change.
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Buffer for temperature-limits extremes
Density
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6. Water expands when freezing.
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Ice less dense than water!!
Lakes and Ponds…
What if…..
Water and Homeostasis?
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What’s that word again?
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How does water help?
7.3- Life Substances
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Organic molecules contain carbon.
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Carbon forms single, double or triple bond.
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Organic molecules have great variety…
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Formulas for compounds may be the
same but differ in structure- isomers
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Also vary in size!
A polymer is a large molecule formed from
bonding of smaller molecules…usually in
long chains
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Carbohydrates
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Organic compounds composed of C, H
and O.
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Monosaccharides-simplest type
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Disaccharides-two monosaccharides
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Polysaccharides-many mono. units
Polysaccharides
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Starch-chains of glucose used as
food storage by plants
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Glycogen-food storage by animals
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Cellulose-cell wall and structural
support for plants
Lipids
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Organic compounds with large
proportion of C-H bonds
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Commonly known as fats and oils
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Insoluble in water
 Composed
of fatty acid chains
attached to a glycerol
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Used for energy storage, insulation and
protection
Saturated vs Unsaturated
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Saturated
1. Chains of Carbon single bonded
 2. Generally solid at room temperature
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Unsaturated
1. Chains of Carbon double bonded
 2. Generally liquid at room temperature
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Proteins
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Large, complex polymer composed of C,
H, O, N, and sometimes S.
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Building Blocks=Amino Acids
20 common AA’s
 Linked by condensation-removal of -H and
-OH groups to form water.
Resulting covalent bond is called a peptide
bond
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Enzymes
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Involved in nearly all metabolic processes
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Enzymes are specific proteins that speed
up chemical reactions
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If there were no enzymes, reactions would not take
place under living conditions
Enzymes have active sites for molecules
to bind to and form a product
Nucleic Acids
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Complex macromolecules that store info.
in cells in the form of a code.
Subunits are called nucleotides
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Consist of C, H, O, N and P atoms
Nucleotides arranged in 3 groups:
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1. Base
2. Simple Sugar
3. Phosphate Group
DNA vs RNA
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DNA-Deoxyribonucleic Acid
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Master copy to any organism’s information
code.
Forms the genetic code
RNA-Ribonucleic Acid
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Copies DNA for protein synthesis