An element is a pure substance which is made of one type of atom. The atom is distinguished by its atomic number, which is equivalent to the number of the protons located in its nucleus. Every object?solid, liquid or gas?is made of an element or combination of elements. Examples of them include hydrogen, helium, carbon, silicon, gold, uranium etc.
The smallest identifiable unit of a compound is a(n) ,which is made up of which are chemically bonded. True of False: A mixture is always made up of a combination of elements. In a mixture, the substances (lose/ retain) their identities. Favorite Answer An element is made up of three or more kinds of matter. Electrons, neutrons and protons. Although in your case the answer is false.
Long ago, people believed that there were four main elements: earth, water, air and fire. However, modern chemistry has proven that there are more. As of March 2010, there are 118 ?discovered? elements on the planet. Some exist naturally, while others are products of various processes to isolate them from their ores and/or generate them from other elements. There are numerous possibilities of undiscovered elements in space.
The atomic number, commonly denoted as ?Z,? is the assigned label of distinction for each element. It refers to the number of protons in the nucleus of an atom. Together with the protons are the neutrons, forming the bulk of the atom?s mass. Revolving around the nucleus are electrons that bear a negative charge, usually containing the atom?s energy.
Some light elements like hydrogen and helium are used by stars as fuels. When their atoms undergo fusion, they can release tremendous heat and energy.
Everything around us is made of elements that are bonded together. Some can even bond in different ways, forming allotropes. For example, pencil graphite is made of carbon. However, if they are bonded in a crystalline structure, carbon can also form diamonds.
An Example Of An Element
The Element Song
An atomic mass (symbol: ma) is the mass of a single atom of a chemical element. It includes the masses of the 3 subatomic particles that make up an atom: protons, neutrons and electrons.
Atomic mass can be expressed in grams. However, because each atom has a very small mass, this is not very helpful. Instead, atomic mass is expressed in unified atomic mass units (unit symbol: u). 1 atomic mass unit is defined as 1/12 of the mass of a single carbon-12 atom.[1]:18 1 u has a value of 1.660 539 066 60(50) × 10−27kg.[2]
A carbon-12 atom has a mass of 12 u. Because electrons are so light, we can say that the mass of a carbon-12 atom is made of 6 protons and 6 neutrons. Because the masses of protons and neutrons are almost exactly the same, we can say that both protons and neutrons have a mass of roughly 1 u.[1]:18 Hence, we can get a rough value of an atom's mass in atomic mass units by working out the sum of the number of protons and the number of neutrons in the nucleus, which is called the mass number. The atomic mass of an atom is usually within 0.1 u of the mass number.
The number of protons an atom has determines what element it is. However, most elements in nature consist of atoms with different numbers of neutrons.[3] An atom of an element with a certain number of neutrons is called an isotope.[1]:44 For example, the element chlorine has two common isotopes: chlorine-35 and chlorine-37. Both isotopes of chlorine have 17 protons, but chlorine-37 has 20 neutrons, 2 more neutrons than chlorine-35, which has 18.[4] Each isotope has its own atomic mass, called its isotopic mass. In the case of chlorine, chlorine-35 has a mass of around 35 u, and chlorine-37 around 37 u.
What Is Made Of Atoms
As mentioned above, note that the atomic mass of an atom is not the same as its mass number. The mass number (symbol: A) of an atom is the sum of the number of protons and the number of neutrons in the nucleus.[1]:20 Mass numbers are always whole numbers with no units. Also, relative isotopic mass is not the same as isotopic mass, and relative atomic mass (also called atomic weight) is not the same as atomic mass.
A relative isotopic mass is the mass of an isotope relative to 1/12 of the mass of a carbon-12 atom. In other words, a relative isotopic mass tells you the number of times an isotope of an element is heavier than one-twelfth of an atom of carbon-12. The word relative in relative isotopic mass refers to this scaling relative to carbon-12. Relative isotopic mass is similar to isotopic mass and has exactly the same numerical value as isotopic mass, whenever isotopic mass is expressed in atomic mass units. However, unlike isotopic mass, relative isotopic mass values have no units.
Like relative isotopic mass, a relative atomic mass (symbol: Ar) is a ratio with no units. A relative atomic mass is the ratio of the average mass per atom of an element from a given sample to 1/12 the mass of a carbon-12 atom.[5] We find the relative atomic mass of a sample of an element by working out the abundance-weighted mean of the relative isotopic masses.[3] For example, to continue the chlorine example from above, if there is 75% of chlorine-35 and 25% of chlorine-37 in a sample of chlorine,[4]
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References[change | change source]
- ↑ 1.01.11.21.3Moore, John T. (2010). Chemistry Essentials For Dummies. Wiley. ISBN978-0-470-61836-3.
- ↑'atomic mass unit'. National Institute of Standards and Technology. Retrieved 2020-01-12.CS1 maint: discouraged parameter (link)
- ↑ 3.03.1Otter, Chris; Stephenson, Kay, eds. (2008). Salters Advanced Chemistry: Chemical Ideas (Third ed.). Heinemann. p. 17. ISBN978-0-435631-49-9.
- ↑ 4.04.1Salters Advanced Chemistry: Revise Chemistry For Salters AS (Second ed.). Heinemann. 2008. p. 3. ISBN978-0-435631-54-3.
- ↑Daintith, John, ed. (2008). A Dictionary of Chemistry (Sixth ed.). Oxford University Press. p. 457. ISBN978-0-19-920463-2.
Other websites[change | change source]
An Element Is Made Up Of Only One Kind Of
- Atomic mass -Citizendium
An Element Is Made Up Of How Many Types Of Atoms