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Why is the atomic mass of elements on the periodic table rarely a whole number?
Wiki User
∙ 12y ago
The mass number is the sum between the number of protons and the number of neutrons in the nucleus of an isotope. The mass number is always a whole number.
You are probably getting confused between mass number, atomic weight and atomic number.
But if you think to atomic weight the answer is:
1. For example, chlorine has a listed atomic weight of 35.453. This is not, however, the mass of every chlorine atom. It is the "average" mass of a chlorine atom. There are two stable isotopes of chlorine, namely 35Cl and 37Cl which exist in the world at the corresponding percentages: (75.78%) and (24.22%). Since roughly one quarter of chlorines have 2 more amu, it makes sense that the atomic weight given is almost 35.5, which would be one quarter of the difference between 37 and 35. It is important to note again, however, that this is an average and not the mass of any actual chlorine atoms. (Also to note, there are other forms of chlorine in very minimal quantities which shift the number slightly, but not noticeably.)
2. Another important cause is the mass deffect (due to the binding energy of nucleons).
Wiki User
∙ 12y ago
Wiki User
∙ 12y agoThe mass number is the sum between the number of protons and the number of neutrons in the nucleus of an isotope. The mass number is always a whole number.
You are probably getting confused between mass number, atomic weight and atomic number.
But if you think to atomic weight the answer is:
1. For example, chlorine has a listed atomic weight of 35.453. This is not, however, the mass of every chlorine atom. It is the "average" mass of a chlorine atom. There are two stable isotopes of chlorine, namely 35Cl and 37Cl which exist in the world at the corresponding percentages: (75.78%) and (24.22%). Since roughly one quarter of chlorines have 2 more amu, it makes sense that the atomic weight given is almost 35.5, which would be one quarter of the difference between 37 and 35. It is important to note again, however, that this is an average and not the mass of any actual chlorine atoms. (Also to note, there are other forms of chlorine in very minimal quantities which shift the number slightly, but not noticeably.)
2. Another important cause is the mass deffect (due to the binding energy of nucleons).
Wiki User
∙ 12y agoIf you think to atomic weights:
1. First cause: the atomic weight is the sum of the weights of protons, neutrons ans electrons.; they don't have masses as integers.
2. Second cause: also occurs the so-called mass defect (binding energy).
Not Atomic Mass for elements; atomic weight is correct.
Wiki User
∙ 12y ago1. For elements the term officially used is atomic weight; atomic mass is only for isotopes.
2. First cause: the weight is the sum of the weights of protons, neutrons ans electrons.; they don't have masses as integers.
3. Second cause: also occurs the so-called mass defect.
Wiki User
∙ 12y ago1. First cause: the atomic weight is the sum of the weights of protons, neutrons ans electrons.; they don't have masses as integers.
2. Second cause: also occurs the so-called mass defect.
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What are the atomicity of the elements in the periodic table?
For chemists the meaning of atomicity is the number of atoms in a molecule. In the past, rarely, the word atomicity was used as an equivalent for valence (if you think to valence the answer is very long for WA for all the elements).
What does the atomic mass minus atomic number tell you about the element?
Atomic mass minus atomic number will give you the average number of neutrons in that element. Bear in mind that atomic mass is based on the actual weight of that element, which is the result of whatever isotopes appear in nature; it is rarely based on only a single isotope.
What distinguishes noble gases from other nonmetals?
Unlikely other elements in the periodic table, noble gases rarely form compounds with other elements.
Does atomic number and atomic mass mean the same thing?
atomic mass and mass number are differernt because atomic mass mean mass of whole atom which mean mass of proton,neutron and electron while mass number is number of proton and neutron only.zahid ullah paf college risalpur
Does the valence electrons equal the number of protons?
Rarely. The number of valence electrons of an element depends on it's position on the periodic table. Any given element can have between 1-8 valence electrons. The number of valence electrons increases left to right on the periodic table, while the number of protons, which determine the atomic mass and identity of an element, increase in general. Therefore the number of valence electrons can only equal the number of protons at the 8th element and below (neon).
Why the mass numbers on the periodic table of elements are rarely whole numbers?
Elements also possess isotopes. So their average atomic mass is rarely whole number.
How are the elements arranged by atomic mass?
They are NOT normally arranged by atomic mass; instead they are arranged in the periodic table by their atomic number. The latter is the number of protons (or electrons) in a single atom of the element and it is a constant for the element. The atomic mass is an average of the isotopes of the element (in proportion to their abundance).While the atomic number is always an integer, increases in steps of 1 and elements that are a specific "distances" apart share similar chemical characteristic. On the other hand the atomic mass is rarely an integer, and occasionally it reverses the order laid out be the periodic table: for example, element 18, argon has an atomic mass of 39.948 which is greater than that of element 19, potassium with a mass of 39.098: this is because the predominant isotope of argon has 22 neutrons while that for potassium has 20 neutrons.
What information does the periodic table provide?
The basic periodic table shows an element's symbol, an atomic number, and they are arranged by it's group which is vertical column, and it's period which is horizontal row. The expanded table gives more information about each element, such as atomic mass, electronegativity and other values. It also tells you the atomic number, how many electrons, and neutrons are there in the symbol. The element. towards the left on the table are metals. The elements towards the right on the table are non-metals. The number of each element has on the periodic table is the number of protons that the element contains. It has the number of outer energy levels.A periodic table can tell you: How many protons, neutrons, and electrons are in a single atom of the element. If it is a metal, metalloid, or a non-metal. How many electrons are in the valence shell. And which family the element belongs to.All of the elements that have been discovered by man. They are listed in order of increasing atomic number, in rows (periods) and columns (groups) that show related characteristics.The periodic table shows the element's symbol and its atomic number, with period and group headings at the side and top, and often colors to designate related groups and subgroups.It tells what an element is classified as and it tells the atomic mass of each elementElement's name, atomic symbol, atomic number & mass, number of neutrons, protons, and electrons, its group, if its a metal nonmetal or metalloid, and number of valence electrons.First of all you can read the atomic number, which is the value of the number of protons in the nucleus and this is equal to the number of electrons of the atomic element.symbol and name of the elementatomic number (hence number of protons / electrons)mass number (hence number of neutrons)electronic configurationwhether the element is solid, liquid or gasWhether the element is metal, metalloid or non-metalSome versions of periodic tables will even list electronegativities or atomic size.The periodic table tells us the Chemical Symbol for each element, the Atomic Weight/Mass, also the name and the charge.The position of each element also corresponds to it's electron configuration, and the relationships of the positions can also be used to understand how they chemically react to one another. Full understanding of the periodic table can be an invaluable reference tool to know what reacts with what, and what kinds of bonds they make, how they position themselves against others in a molecule, and more. Sadly, rarely are these traits of the periodic table taught.
What are the atomicity of the elements in the periodic table?
For chemists the meaning of atomicity is the number of atoms in a molecule. In the past, rarely, the word atomicity was used as an equivalent for valence (if you think to valence the answer is very long for WA for all the elements).
What does the atomic mass minus atomic number tell you about the element?
Atomic mass minus atomic number will give you the average number of neutrons in that element. Bear in mind that atomic mass is based on the actual weight of that element, which is the result of whatever isotopes appear in nature; it is rarely based on only a single isotope.
What distinguishes noble gases from other nonmetals?
Unlikely other elements in the periodic table, noble gases rarely form compounds with other elements.
Where is neon located on the periodic table?
Because its atomic number is what it is. The Periodic table of elements was arranged so that the scientist could easily scan it and identify an unknown substance by its atomic number or number of protons. In uncomplicated terms, Neon (Ne) has one less proton than Sodium (Na), but one more than Fluorine (F).
Does atomic number and atomic mass mean the same thing?
atomic mass and mass number are differernt because atomic mass mean mass of whole atom which mean mass of proton,neutron and electron while mass number is number of proton and neutron only.zahid ullah paf college risalpur
Does the valence electrons equal the number of protons?
Rarely. The number of valence electrons of an element depends on it's position on the periodic table. Any given element can have between 1-8 valence electrons. The number of valence electrons increases left to right on the periodic table, while the number of protons, which determine the atomic mass and identity of an element, increase in general. Therefore the number of valence electrons can only equal the number of protons at the 8th element and below (neon).
What family is group 18 on the periodic table of elements?
The Noble Gases-because they rarely combine with other elements and are found only as uncombined elements in nature.
Which group in the periodic table contains elements that do no react easily to form chemical compounds?
Group 18 elements, which are also known as noble gases, rarely form chemical compounds.
What are general properties of the elements in the group to the right in the Modern Periodic Table?
Group 18 is the group farthest to the right on the periodic table. The elements in group 18 are also known as the noble gases. Noble gases are gases at standard temperature and pressure. Also, since they have their full complement of valence electrons they rarely make compounds with themselves or other elements.
