Download Chapter 2 The Chemistry of Life

Section 2.1
 What three subatomic particles make
up atoms?
 How are all of the isotopes of an
element similar?
 What are the two main types of
chemical bonds?
2.1 Vocabulary
atom
nucleus
electron
element
isotope
compound
ionic bond
ion
covalent bond
molecule
van der Waals forces
Chapter 2 The Chemistry of Life
 Atom – the building blocks of matter
(100 million atoms side by side = 1 cm in length)
Subatomic particles in the atom:
1. Protons
Inside the ________________
2. Neutrons
3. Electrons
electron
neutron
proton
 Protons – positive charge (atomic #)
 Neutrons – neutral (no charge)
 Electron – negative charge
 Protons and neutrons about the same
mass
 Electron is very small (1/1840 mass of
proton)
 Electrons in constant motion around
the nucleus
 Elements in the human body
 # Protons = # electrons
 Overall charge of atom is _________
 Proton # also called the _____________
________________.
Elements
Pure substance
Made of one type of atom
More than 100, but only about 25 in
living organisms
The Periodic Table of Elements
 Interactive
Isotopes
 Atoms of the same element that have a
different number of neutrons
 Identified by their mass number
example: C-12
C-13
C-14
 All isotopes of an element have the
same chemical properties b/c same
number of electrons
Radioactive Isotopes
 Nuclei are unstable and break down at a
constant rate over time
 Important scientific/practical uses
 Geologists determine age of rocks and
fossils
 Treat cancer
 Kill bacteria that cause food to spoil
 Labels (tracers) to follow movements of
substances in organisms
Chemical Compounds
 Substance formed by the chemical
combination of 2 or more elements
 Combine in definite proportions
 Use chemical formulas to identify them
(H2O, NaCl)
 Physical and chemical properties of a
compound are different from the elements
making it up
Chemical Bonds
 Bonding involves the electrons in the atoms
 Ionic Bond forms when electrons are
transferred from one atom to another
 Cation-an atom that loses electrons, positive
charge
 Anion-an atom that gains electrons,
negative charge
Ionic Bond
 NaCl
Covalent Bonds
 Electrons are shared between atoms
 Single bond ______ electrons shared
 Double bond ______ electrons shared
 Triple bond _______ electrons shared
 Molecule- smallest unit of most compounds
-formed when atoms bond
covalently
Covalent Bond
 H2O
van der Waals forces
 Intermolecular forces of attraction
 Molecules get close together and attraction develops
between oppositely charged regions of nearby
molecules
 Gecko, pg. 39
Gecko
Gecko’s foot
covered by half a
million tiny setae
Comes in contact
with a large area of
the wall at
molecular level
The Water Molecule
 Polar
Cohesion
Attraction between
molecules of the same
substance
Adhesion
Attraction between
molecules of different
substances
Capillary action
Solutions & Suspensions
Mixtures
Solutions
Solute
Solvent
Suspension
Mixture of water and nondissolved material
Acids, Bases, pH
Water  Hydrogen ion +
Hydroxide ion
pH Scale shows concentration of
Hydrogen ions in solution
Acidic solutions
Basic solutions
Buffers
Control pH to maintain
Homeostasis
Carbon Compounds (2.3)
Organic Chemistry
Carbon has 4 valence
electrons
Macromolecules
“giant molecules”
Formed by polymerization
Small units (Monomers) join
together to form polymers
Four groups of Organic Cmpds.
Found in Living things
1. Carbohydrates - made up of C, H, O 1:2:1
 Main source of energy for living things
 Structural in plants and some animals
 Glucose broken down, supplies energy
 Extra sugar stored as complex CHO
STARCH
starch = polymer
sugar molecules = monomers
Monosaccharides
-single sugar molecule
-glucose, galactose, fructose
Polysaccharides
-formed from monosacc.
-extra sugar stored in glycogen
Carbohydrates
Starch
Glucose
Lipids
 Insoluble in water
 Made mostly from C and H
 Fats, oils, waxes
 Used to store energy
 Part of biological membranes and
waterproof coverings
 Steroids (chemical messengers, ex.
cholesterol) are lipids
Structure of Lipids
Glycerol + fatty acids (fig.2-14)
Saturated-each C in the F.A. is
joined to a C by single bond
(F.A. contains the max. no. H
atoms)
Unsaturated-at least one C-C
double bond in the F.A.
Polyunsaturated-F.A. contains
more than one double bond
Unsaturated-liquid at room
temp.
Cooking oils = polyunsaturated
Nucleic Acids
Macromolecules made up of H,
O, N, C, P
Polymers assembled from
nucleotides (monomers)
Nucleotides made of 3 parts:
1.
2.
3.
Nucleic acids
Store and transmit genetic
information
Two kinds of N.A.
1. RNA (ribose)
2. DNA (deoxyribose)
The structure of a nucleic acid
Nucleotide
Nucleotides
Adenine
Thymine
Cytosine
Guanine
Proteins
 Macromolecules, contain C, H, O, N
 Made up of amino acids
-amino group
-carboxyl group
-More than 20 different A.A. in nature
-the side chain called the R-group is
different
Functions of Proteins
Control rate of reactions
Regulate cell processes
Used to form bones, muscles
Transport materials into or out of
cells
Help fight disease
Up to 4 levels of organization