Transcript Synthesis reactions - Brookwood High School

Chemistry Alive: Review of
Basic Concepts
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Concepts of Matter
• Anything that occupies space and has mass
• Mass remains constant but weight varies
with gravity
• Matter can be seen, smelled and/or felt
• Solid, liquid or gas
• Matter can be changed physically or chemically
• Liquids conform to the shape of the container
• Gas- no definite shape nor definite volume
Composition of Matter
• Matter is composed of • 96 % of body weight
substances called
is made up of 4
elements
elements
• Elements cannot be
Carbon, Oxygen,
broken down into
Hydrogen, Nitrogen
simpler substances
• Atoms are the
by ordinary chemical
building blocks of
methods
elements- identical
particles
Elements and Atoms
• Pure substances like carbon, hydrogen and
oxygen that are composed of only one type of
atom are classified as elements.
• Element is designated by a one- or two- letter
chemical shorthand called the atomic symbol, C
is for Carbon, Na is for sodium
• Atom is derived from the Greek word meaning
“incapable of being divided”
• If an atom is split into its sub particles it loses the
unique properties of its element
Elements of Life
Element
Oxygen
Atomic %
Symbol
O 65
Role
Carbon
C
Hydrogen
H
9.5
Ionic form influences the pH of body
fluids. Component of most organic
molecules
Nitrogen
N
3.2
Component of proteins and nucleic
acids
Component of organic and inorganic
molecules. Oxidation of glucose
18.5 Primary element Of all organic
molecules
Element
Calcium
Atomic %
Symbol
1.5
Ca
Phosphorus
P
1.0
Potassium
K
0.4
Sulfur
S
0.3
Na
0.2
Sodium
Role
Salt in bones and teeth; ionic form
required for muscle contraction,
neural transmission and blood
clotting
Salt, in combination with Ca in
bone and teeth. Nucleic acids,
proteins; forms part of ATP
Ionic form major intracellular cation
(+) ;nerve impulses and muscle
contraction
Component of contractile proteins
of muscle
Major extra cellular cation; water
balance, nerve impulses and
muscle contraction
Element
Chlorine
Atomic % Role
Symbol
Cl
0.2 Major extra cellular anion(-)
Magnesiu
m
Iodine
Mg
I
0.1 Bone; cofactor for enzyme
activity
0.1 Needed to make functional
thyroid hormones
Iron
Fe
0.1 Component of functional
hemoglobin molecule
Trace elements less than 0.1 %: Cr, Co, Cu, Fl, Mn, Mo, Se, Si,
Sn, V, Zn; Many found as part of enzymes or required for
enzyme activation
Molecular Substances
I.
When two or more atoms are chemically
bonded a molecule is formed.
II. Two atoms of the same element bond together an
element is produced. I.e. O2, H2
III. Two or more different atoms form molecules of a
compound, CH4
IV. Molecule is the smallest part of a compound that
retains the features of that compound
Compounds
• A compound is a substance made from two or more elements
which have reacted chemically with each other.
For example : The element sodium is a highly reactive metal and
the element chlorine is a yellow-green poisonous gas (nonmetal). When the two react together, they form a compound
called sodium chloride. Sodium chloride is common salt, which
you eat with food.
Chemical Bonds
• Ionic
– Electron transferred
• Covalent
– Electron shared
• Hydrogen (polar
covalent)
– Electron shared
unequally
Chemical Reactions
reaction where reactants and products are balanced
C6H12O6 + 6O2  6CO2 + 6H2O + ATP
•When reactions take place, there is an exchange of energy.
• Whenever chemical bonds are broken, energy is released.
•When new bonds are formed, energy is stored.
•Sometimes [when the energy stored in the new bonds of the
products is less than the energy released from the reactants]
energy is released during a reaction. This energy may be given off
as heat, or it may be used to do work.
•Sometimes, the products of the reaction store more energy in
their chemical bonds than the reactants had stored. This stored
energy can be held for later use.
Chemical Reactions
All chemical reactions involve atoms trying to get
a full outer shell of electrons.
When an atom reacts with another atom, it will either
1. Lose electrons to form a stable positive ion.
2. Gain electrons to form a stable negative ion.
3. Share electrons to form a stable molecule.
Key to chemical reactivity is the rule of 8s. ( Octet Rule)
Synthesis reactions
As an example of a synthesis reaction :
Ca + S -------------------> CaS
The + sign means "reacts with" or "combines with"
and the arrow indicates "to form".
Synthesis Reactions: Summary
• Involve bond formation
• Energy-absorbing reactions
• Underlie all anabolic (constructive)
activities in body cells
• Growth and repair of worn-out or
damaged tissues
Decomposition reactions
An example of a decomposition reaction is :
The products of this decomposition reaction
have quite different chemical properties to
the initial compound.
Decomposition Reactions
•
•
•
•
•
•
Bonds are broken
Chemical energy is released
Catabolic (destructive) processes
Molecule-degrading reactions
Digestion of food into building blocks
Breakdown of glycogen to release glucose
Exchange Reactions
• Involves both synthesis
and decomposition
reactions
• Bonds are both made and
broken
• ATP reacts with glucose
forming glucosephosphate
and ADP
• AB + C
AC + B
• AB + CD
AD +CB
Chemical Reactions
• If a reaction releases energy it is exergonic
• If a reaction absorbs energy it is endergonic
Catabolic and oxidative reactions are for
the most part exergonic
4 Factors influencing chemical rxns
• Temperature: An increase in temperature
increases the kinetic energy therefore the
reactions are quicker
• Amount: As the concentration of reactants
decline we reach chemical equilibrium
• Size: Smaller particles move faster, hence
faster reactions
• Catalysts: increase a reaction without being
used up, enzymes