Transcript The Chemistry of Life

1. Review- What is a compound
Apply Concepts- Water (H2O) and hydrogen
peroxide (H2O2) both consists of hydrogen and
oxygen atoms. Explain why they have different
chemical and physical properties
2. Big Idea- Why do you think it is important that
biologist have a good understanding of
chemistry?
CH 2 THE CHEMISTRY OF LIFE
2.1 The Nature of Matter
Biology Class


You take Chemistry next year so why learn about it
now
Chemistry is essential to all living things.



What are you made of
When you breathe, eat, or drink, your body uses
the substances in air, food, and water to carry out
chemical reactions that keep you alive
Water freezing to you moving your muscles to
processing thoughts.
Atoms


Basic unit of matter
May be broken into smaller particles that do NOT
have the properties of the element.
Atoms


Very small- 100 million atoms would make a row
only about 1 centimeter long
Consists of protons, neutrons, and electrons.
Atoms

Nucleus
 Core

of atom
Protons
 Positive

Neutrons
 No

charge, in nucleus, mass of 1 atomic unit
charge, in nucleus, mass of 1 atomic unit
Electrons
 Negative
charge, orbits nucleus, mass of 0 atomic units
(technically a mass of 1/1840).
Carbon Atom

Atoms have equal
numbers of electrons
and protons, their
positive and negative
charges balance out,
and atoms themselves
are electrically
neutral.





Matter is made up of atoms
Atoms join together to make compounds
Compounds use chemical bonds to hold them
together
Chemical bonds are stored energy
Molecule
 Atoms
of the same element joined together.
Elements and Isotopes


Elements and isotopes have same number of
electrons
All isotopes of an element have the same chemical
properties.
Elements



Pure substance that
consists entirely of one
type of atom or
Elements cannot be
broken down into other
types of substances
Mercury (Hg).
Isotopes

Atoms of the same element that differ in the
number of neutrons.

Atomic number
 Number

of protons
Atomic Number
(atomic mass or
weight)
 Number
of protons
and neutrons.
Carbon Atom

Atomic Number
6

Mass Number
 12
Radioactive Isotopes


Nuclei are unstable and break down at a constant
rate over time
Used for
 Determine the
ages of rocks and fossils by analyzing
the isotopes found in them
 Detect and treat cancer
 Kill bacteria that cause food to spoil
 Labels or “tracers” to follow the movements of
substances within organisms.
Chemical Compounds


Substance formed by the chemical combination of
two or more elements in definite proportions
Water, the chemical formula H2O, contains two
atoms of hydrogen for each atom of oxygen.
Chemical Compounds


Physical and chemical properties of a compound
can be different from the elements that forms it
Sodium
 Reacts

explosively with cold water
Chlorine
 Very
reactive, poisonous, greenish gas that was used in
battles during World War I

Sodium Chloride
 Table
salt.
Chemical Bonds



Attraction between two atoms resulting in a
sharing or transferring of an electron(s)
Uses electrons
Covalent Bond
 Chemical

Ionic Bond
 Chemical

bond that SHARES electrons
bond that TRANSFERS electrons
Hydrogen Bond
 Weak
bond between hydrogen ions.
Covalent Bonds

Shares electron(s).
Ionic Bond


Transfer of electron(s)
Ion
A
charged particle
 Protons do NOT equal electrons
Ionic Bond

A sodium atom easily loses its one valence electron
and becomes a sodium ion (Na+).
Ionic Bond

A chlorine atom easily gains an electron (from
sodium) and becomes a chloride ion (Cl-).
Van der Waals Forces



Slight attraction can develop between the
oppositely charged regions of nearby molecules
Due to unequal sharing of electrons within each
molecule
Much weaker than Covalent of Ionic bonds.