Elements and Compounds

What is the composition of matter?



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Matter is anything that has mass and volume. The mass of matter is measured by the acceleration a body has when a force is applied. The greater the mass, the slower the acceleration for the same force. The volume is determined by the space in three dimensions that it occupies.

Einstein showed that ultimately all matter is capable of being converted to energy, by the formula

E = mc2

Where E is the energy comprising a piece of matter of mass m, times the c2 the speed of light squared (multiplied by itself). As the speed of light is exactly 299,792,458 metres per second or 186,272 miles per second, just a little matter is comprised of a lot of energy.

Everything we see is comprised of atomic matter, made up of sub-atomic particles, usually a nucleus of protons, neutrons and a cloud of orbiting electrons. When atomic matter is hot enough it ionises (or loses its electrons, usually above about 5,000degrees C) and this causes it to emit the energy of light. The light we see by in this way usually comes from the sun (or other stars at night), either by daylight or by fossil fuels, stored from sunlight captured many millions of years ago. Atomic matter at lower temperatures also can reflect light, absorbing some at specific wavelengths, which determines the colours of the objects we see.

The WMAP probe, which examined the cosmic microwave background of the universe, enabled us to determine only 4% of the Universe is comprised of ordinary atomic matter, the remainder is either Dark Matter (23%), believed to be weakly interacting massive particles, and Dark Energy (73%) causing an acceleration in the speed with which the universe is expanding. Of the 4% of the composition of the Universe, 0.6% is in luminous stars, the other 3.6% is comprised of clouds of non luminous interstellar dust and gas.

Atomic matter is found in the form of one of 111 elements, which differ by their nuclear composition. The simplest element, hydrogen, comprises one proton in its nucleus, and one orbiting electron. Helium, the next most simple element generally contains a nucleus of two protons, and two neutrons, with two orbiting electrons. Immediately after the big bang, the universe comprised of 90% hydrogen atoms, 10% helium atoms (by weight 75% hydrogen and 25% helium). Since then all other elements of atomic matter, including most of your body, have been made in the heart of ancient stars.

The 10 most common elements in the universe by mass are

ELEMENT.........Parts per million











Antimatter is matter comprised of the anti-particles of ordinary matter. There is very little antimatter in the universe today, but when the universe was formed, 499 parts of every 1000 were particles of antimatter, which was annihilated through contact with particles of ordinary matter, leaving the 2 parts per 1000 as the atomic matter we see today.

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