Chemistry

MATTER AND ENERGY

Matter- anything that occupies space and has mass (weight)

Energy- the ability to do work

* chemical * electrical * mechanical * radiant

Chemistry

1. science of all the structure and interaction of matter. 2. all living things consist of matter.

Elements- composed of chemically identical atoms

1. bulk elements- required by the body in large amounts 2. trace elements- required by the body in small amounts

Atoms- smallest particle of an element

Mass- amount of matter in any object

HOW MATTER IS ORGANIZED

Weight- the force of gravity acting on matter

Outer space:

1. weight is close to zero 2. mass remains the same as on earth

Elements

* substances that can not be split into simpler substances. * 112 elements (92 occur naturally) * 26 of naturally occuring elemens are in the body * chemical symbols: * * first 1-2 letters of name

* fundamental units of matter * 96% of the body is made from four elements

Atoms- building bocks of elements

* smallest units of element or mattetr * 3 types of subatomic particles: * 1. protons = + charge 2. neutrons = no charge 3. electrons = - charge

98.5% of the total body weight is formed by 2 elements : calcium and phosphorus

ELECTRONS AND BONDING

Electrons occupy energy levels called electron shells

Electrons closest to the nucleus are the most strongly attracted

Each shell has distinct properties

* The number of electrons has an upper limit * Shells closest to the nucleus fill first

INERT ELEMENTS

Atoms will gain, lose, or share electrons to complete their outermost orbitals and reach a stable state

Rule of eights:

* Atoms are considered stable when their outermost orbital has 8 electrons * The exception to this rule of eights is: * * Shell 1=holds only 2 electrons

Atoms are stable (inert) when the outermost shell is complete

HOW TO FILL THE ATOM'S SHELLS

* Shell 1 can hold a maximum of 2 electrons * Shell 2 can hold a max of 8 electrons * Shell 3 can hold a maximum of 18 electrons

IDENTIFYING ELEMENTS

Atomic number:

1. number of protons = the number of electrons

Atomic mass number

1. sum of the protons + neutrons

Isotopes

* Have the same number of protons and atomic number * different number of neutrons

Atomic weight

* Close to mass number of most abundant isotope * Atomic weight reflects natural isotope variation

Radioisotope

* Heavy isotope * tends to be unstable nucleus decay over time * decomposes to more stable isotope

Radioactivity

* process of spontaneous atomic decay

ISOTOPES : RADIATION

Effects of Radiation

1. Release small amounts of radiation naturally 2. Radon-222 gas seeps from the soil 3. increase cancer risk

Helpful

1. medical imaging 2. treating cancer

IONS, MOLECULES, AND COMPOUNDS

Ions

1. formed by ionization 2. atoms that gave p or gained an electron 3. written with its chemical symbol (+) or (-)

Molecule

1. two or more atoms of the same elements combined chemically 2. share electrons

Compound

1. two or more atoms of different elements combined chemically 2. atoms with the same element

Molecule

1. written as molecular formula:

1. shows the number of atoms of each element

2. examples

1. water (H2O) 2. sodium chloride (NaCl)

STRUCTURAL FORMULA

H H \ / O=C=O O H2O CO2

FREE RADICALS

Electrical charged atom or group of atoms with an unpaired electron in its outermost shell

Unstable and highly reactive

Can be stable:

1. by giving up electron taking one off another molecule

Produced in your body by absorption of energy in ultraviolet light in sunlight, x-rays

Linked to many diseases -- cancer, diabetes, Alzheimer, atherosclerosis and arthritis.

Damage may be slowed with antioxidants

1. vitamins C