![]() Some seem to make no sense at all, like lead (Pb), silver (Ag), and gold (Au). Some are obvious, like hydrogen (H), oxygen (O), carbon (C), uranium (U), helium (He), or calcium (Ca). Glucose molecules (C 6H 12O 6) have atoms of the elements carbon, hydrogen, and oxygen in them.Īll of the elements have one- or two-letter abbreviations. Glucose, a simple sugar, is another example of a compound. Water (H 2O) is probably the best-known compound it has two different types of atoms (elements) in it, hydrogen (H) and oxygen (O). Since they have more than one type of atom, these substances are NOT elements they are called compounds. ![]() Many common substances are made of molecules that consist of two or more different types of atoms. Oxygen is also the most abundant element by mass in Earth's crust, and the second most abundant gas (after nitrogen) in our planet's atmosphere. You are truly a "child of the Universe"! Oxygen and carbon are the third and fourth most abundant elements in the Universe. Pretty much all of the other elements, including much of the stuff that makes up your body, were created in supernova explosions of dying stars. Both formed soon after the Big Bang that gave birth to the Universe. Hydrogen is the most common element in the Universe, followed by helium. Scientists measure the ratio of 12C to 14C in objects to tell how old they are. Radioactive carbon-14 ( 14C) has 6 protons plus 8 neutrons. Most natural carbon is carbon-12 (or 12C) it has 6 protons and 6 neutrons. A radioactive isotope of carbon is often used to figure out how old things are using a technique called " carbon dating". An isotope of hydrogen called "deuterium" has one proton plus one neutron in its nucleus. For example, normal hydrogen has just one proton and no neutrons in its nucleus. Such atoms are called " isotopes" of the element. An atom of an element might have different numbers of neutrons in its nucleus. Most elements come in more than one variety. As of 2007, there were 117 know elements, 22 of which were created by people. Humans have been able to make many other new elements that don't occur in nature, usually by crashing atomic nuclei together at super high speeds in particle accelerators. All of them, plus one other (californium) have been detected in space. There are 94 different elements that we know of which occur in nature on Earth. Hydrogen, helium, oxygen, nitrogen, carbon, gold, silver, lead, and uranium are well-known examples of elements.Ĭhemists use a special type of chart, called the " periodic table", to organize the elements into groups based on similar chemical properties. ![]() An element (also called a "chemical element") is a substance made up entirely of atoms having the same atomic number that is, all of the atoms have the same number of protons.
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