Transcript Bio02 Chemistry

The Basics Of Life
Chemistry
Matter, Energy, and Life
All life forms are composed of matter
and use energy to carry out processes.
Matter is anything that has mass.
Energy is the ability to do work.
Chemistry
Chemistry is the science concerned
with the study of the composition,
structure, and properties of matter and
the changes it undergoes.
Both living matter and non-living matter
have the same basic building blocks.
Two General Types of Energy
Kinetic energy is the energy of
motion.
Potential energy is stored energy. It
is energy that is not yet doing work.
Potential energy is stored in matter and
chemicals. It can be converted to
kinetic energy to perform some sort of
work.
1st Law of Thermodynamics
The 1st law of thermodynamics is also
known as the law of conservation of
energy.
Energy is never created or destroyed.
Energy can be converted from one form
to another, but the total energy remains
constant.
Five Forms of Energy
1. Mechanical.
2. Nuclear.
3. Electrical.
4. Radiant.
5. Chemical.
All of these forms can be either kinetic
or potential.
Mechanical Energy
Mechanical energy is associated with
machines or things in motion.
Mechanical energy becomes kinetic
when objects come into motion.
Nuclear Energy
Nuclear energy is energy from
reactions at the atomic nucleus of
matter.
Electrical Energy
Electrical energy (electricity) is the
flow of charged particles.
All metabolic reactions involve electrical
energy.
Radiant Energy
Radiant energy takes many forms
including, but not limited to, the
following:
Heat
Visible light
X-radiation
Microwaves
Chemical Energy
Chemical energy is a type of potential
energy stored in matter.
When chemicals are changed from one
form to another, it is released as kinetic
energy.
Cellular respiration is the method
living things utilize to release chemical
energy.
Atom
Atoms are the smallest units of matter
that can exist alone.
Elements are fundamental chemical
substances made up of collections of
only one kind of atom.
There are over 100 different elements.
Structure of the Atom
3 major subatomic particles:
Neutrons.
Protons.
Electrons.
Atomic nucleus – the central core of the
atom where the mass is concentrated.
Subatomic Particles
Neutron – a heavy subatomic particle that
does not have a charge. Located in the
atomic nucleus.
Proton – a heavy subatomic particle with a
positive charge. Located in the atomic
nucleus.
Electron – a light subatomic particle with a
negative charge that moves around the
outside of the nucleus in energy levels.
Atomic Number
All atoms of an element have the same
number of protons.
The atomic number of an element is
the number of protons in an atom of
that element.
Each element has a unique atomic
number.
Atomic Mass Unit
The mass of a proton is 1.67 x 10-24
grams.
Since this mass is awkward to express,
1 proton is said to have a mass of 1
atomic mass unit (AMU).
Neutron Number
All atoms of the same element have the
same number of protons and electrons;
However, they do not always have the
same number of neutrons. They can
have more or fewer neutrons.
Each atom of the same element with a
different number of neutrons is called
an isotope of that element.
Atomic Weight
The atomic weight of an element is
an average of all the isotopes present in
a mixture in their normal proportions.
Mass Number
The number of protons and neutrons in
the nucleus of an atom is called the
mass number.
Comparison of Atomic
Particles
Protons
Neutrons Electrons
Location
Nucleus
Nucleus
Outside
nucleus
Charge
Positive
(+)
None (neutral)
Negative
(-)
Number
Present
Identical to
Atomic #
Atomic Weight Equal to # of
Minus Atomic # protons
Mass
1 AMU
1 AMU
1/1,836 AMU
Periodic Table of the Elements
The table provides information about
all known elements.
The atomic weight increases as you
read left to right along the periods.
Families go from top to bottom and
consist of elements with similar
chemical properties.
1st Draft of the Periodic Table by
Dmitri Mendeleev (1834-1907)
Elements in Living Things
11 main elements comprise living
things.
C, H, O, P, K, I, N, S, Ca, Fe, and Mg.
CHOPKINS CaFé, Mighty Good!
Position of Electrons
Electrons occupy certain areas around
the nucleus known as energy levels.
Each energy level contains electrons
movement at about the same speed
(approximately the same level of kinetic
energy).
Position of Electrons
Energy levels are numbered in increasing
order with level 1 closest to the nucleus.
Electrons move in spherical or figure 8
patterns around the nucleus.
The first energy level is full when it has 2
electrons, the second energy level is full
when it has 8, the third level 8, and so on.
Octet (8) Rule
The octet rule states that atoms seek
a stable, filled outer energy level.
Hydrogen and Helium have a filled
outer energy level with 2 electrons;
However, all other atoms have 8
electrons in their outer energy levels.
Octet (8) Rule
Atoms attempt to acquire this stable
level through chemical reactions with
other atoms.
Atoms such as He and Ne have full
outermost energy levels. Therefore
they normally do not undergo chemical
reactions. They are referred to as
noble or inert.
Valence Shell
The valence shell is the outermost shell of
an atom in its uncombined state.
The electrons of the valence shell are the
ones that are most likely to contribute to
chemical reactions and bond with other
atoms.
Electrons in this shell are referred to as
valence electrons.
Molecule
A molecule is the smallest particle of a
chemical compound that is a definite and
distinct, electrically neutral group of bonded
atoms.
Some atoms bond to form diatomic
molecules (di = two). H2, O2, and N2 are
diatomic gases in our atmosphere.
Some elements such as the noble gases He
and Ne exist as monatomic elements.
Compound
A compound is a chemical substance made
up of two or more elements combined in a
specific ratio and arrangement.
Chemical bonds are the attractive forces
that hold atoms together.
Molecules can consist of two or more atoms
of the same element (i.e. N2 or O2) or specific
numbers of different elements.
Formula
The formula of a compound tells us:
What elements it contains.
The proportions of these elements.
H20.
Molecules and Kinetic Energy
All matter has kinetic energy.
Molecules are in constant, random
motion.
They diffuse from areas of high
concentration to areas of low
concentration.
The rate of diffusion is dependent upon
the temperature of the room.
Temperature Vs. Heat
Temperature is a measure of the average
kinetic energy of the molecules making up a
substance.
Heat is the total internal kinetic energy of
molecules, which is measured in calories.
A calorie is the amount of heat necessary to
raise the temperature of 1 gram of water 1
degree Celsius.
Temperature Vs. Heat
Heat is a quantity of energy.
Temperature deals with comparative
hotness or coolness of things (how fast
molecules are bumping into one
another or their kinetic energy).
Adding heat to molecules will increase
their temperature.
Phases of Matter
The phases of matter are determined by the
following:
The amount of kinetic energy molecules have.
The strength of the attractive forces between
molecules.
The arrangement of the molecules.
Three phases:
Solid.
Liquid.
Gas.
Solid
A solid consists of molecules with
strong attractive forces and low kinetic
energy.
The molecules vibrate in place and are
at fixed distances from one another.
Liquid
A liquid has molecules with enough
kinetic energy to overcome the
attractive forces that hold the molecules
together.
The molecules are still strongly
attracted to one another, but they are
slightly farther apart.
Liquid
The molecules can slide past one
another.
Liquids change shape, but they
maintain their volume.
Liquids flow and are called fluids.
Gas
A gas is made of molecules that have a
great deal of kinetic energy.
The attraction of the molecules to one
another is overcome by the speed with
which the individual molecules move.
Gas
The molecules collide against one
another and push each other apart.
Therefore, gases expand to fit their
container.
Vapor is the gaseous form of a
substance that is usually in a liquid
phase.
Chemical Reaction
A chemical reaction is a change in
matter in which different chemical
substances are created by either
forming or breaking chemical bonds.
A chemical reaction involves atoms
interacting with other atoms to fill their
outermost energy level with electrons.
Chemical Reaction
The interacting atoms become attached
or bonded to one another.
Two types of bonds:
Ionic.
Covalent.
Ionic Bonds
A positively or negatively charged atom
or molecule is called an ion.
Ionic bonds are formed after atoms
transfer electrons to achieve a full
outermost energy level.
Electrons are donated or received
during the transfer to form positive and
negative ions (ionization).
Covalent Bonds
A covalent bond is a chemical bond
formed by the sharing of electrons.
A covalent bond in which a single pair
of electrons is shared is called a single
covalent bond (single bond).
Double bond – two pairs of electrons
are shared by two atoms.
Triple bond – three pairs.
Hydrogen Bonds
Hydrogen bonds are due to the unequal
sharing of electrons and the resulting polar
nature of the molecule.
Hydrogen bonds can be either intermolecular
or intramolecular.
Hydrogen bonds hold molecules together,
they do not bond atoms together. Therefore,
they are not true chemical bonds.
Mixtures and Solutions
A mixture is matter that contains two
or more substances that are not in set
proportions.
A solution is a liquid mixture of ions or
molecules of two or more substances.
The process of making a solution is
called dissolving.
Mixtures and Solutions
The solvent is the component present in
the larger amount.
The solute is the component that
dissolves in the solvent.
Aqueous solution – solid, liquid or
gas dissolved in water.
The amounts of solute and solvent are
the concentration of a solution.