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