Tuesday, September 22, 2009

Atomic Clock

Here are my thoughts about the atomic clock.

An atomic clock is a clock that kind of an atomic resonance frequency standard as your accountant. While the time base of a conventional clock is that the pendulum, the atomic clock is based on the properties of atoms in the transition between different energy states.

The first person to express the concept of the atomic clock is Columbia University, Isidor Rabi in 1945. He suggested that a clock can be made from a technique developed in the 1930s called atomic beam magnetic resonance. In 1949, the National Bureau of Standards introduced the world atomic clock, first with the ammonia molecule as the source of the vibration, and the first atomic clock using cesium atoms as the vibration source announced in 1952.

Both conventional watches and atomic clocks use oscillations to monitor the passage of time. The vibration frequencies within the atom depends on the mass of the core and the gravity and electrostatic "spring" between the positively charged nucleus and the electron cloud around it.

The most accurate atomic clocks available today use cesium atom and normal magnetic fields and detectors. Cesium-133 is the most chosen for atomic clocks. The operation of a cesium-beam atomic clock is based on the transition between two states in the cesium atom. Rubidium is also used in atomic clocks, and reduces the cost, however, less stable rubidium clocks. Hydrogen maser short-term stability and low long-term precision. Mercury ion is also used in some of the atomic clocks. A particular isotope of Ytterbium has a particularly precise resonant frequency in one of the hyperfine transitions. Strontium has a hyperfine transition that is not correct. Strontium can be powered by solid-state lasers can be used for a very low cost, long life and compact clock making. Cesium atomic clocks are used in laboratories, such as the National Institute of Standards and Technology to keep the national timetables.

Thursday, September 3, 2009

The Structure of Atom

These are some facts about the structure of atom.

Before discussing the structure of atoms, we must learn the words mass and weight. If we on the moon, our weight will be less, but our mass is the same. It is said that if you want to lose weight, go to My To lose weight, dieting and exercise. For our purpose in this article, the mass and weight terms are used interchangeably, because we are on earth.

Hydrogen, helium, carbon, nitrogen called elements. There are just over 100 known elements, and are included in the periodic table. All matter is composed of various combinations of these 100 + PIECES. If water is composed of two elements, hydrogen and oxygen. Each water molecule contains two atoms of hydrogen and one atom of oxygen - H2O.

All atoms have a nucleus with electrons zooming around. It can be compared to planets (electrons) move around the Sun (nucleus.)

The nucleus contains most of the mass or weight of the atom. The key to finding the protons and neutrons. The number of protons of each type of atom is the same. For hydrogen atoms, for example always a proton. Helium atoms are always two protons. All carbon atoms have six protons. All nitrogen atoms have seven protons, etc.

The periodic table is arranged in numerical order, depending on the number of protons, atoms of the element have. This number is the atomic number. Hydrogen has atomic number 1. The atomic number of helium 2. The atomic number of carbon 6. The atomic number of nitrogen 7, etc.

The number of neutrons in the atoms changes. Helium atoms are sometimes 2 neutrons and others have 3 neutrons. The atoms of carbon and other sometimes 6 neutrons 7 neutrons. Nitrogen atoms have 7 neutrons and others have 8 neutrons, scientists, etc. to calculate an average.

If you add up the number of protons and neutrons in the mean of an atom, you get the atomic mass or atomic weight or mass number. These three terms refer to the same. If you look at a periodic table, you will see that the mass number of helium is 4003, the atomic mass of carbon is 12.01, the atomic weight of nitrogen is 14.01, etc.

Protons have a positive charge. Neutrons have no charge they are neutral. Electrons have a negative charge. In an electrically neutral atom, the number of electrons and protons are equal, balancing it out in neutral. Electron little mass or weight. Electrons zooming around outside the nucleus in orbitals and to take part in chemical reactions. The protons and neutrons remain where they are located in the nucleus. They do not take part in chemical reactions.
Bookmark and Share