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Atomic Mass accounts for the average mass of all of the different isotopes of an atom of a given element and their relative abundance in nature. Therefore, as the number that appears on the Periodic Table is only an average, there are decimal places included.
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Why do you need atomic numbers?
It tells you how many protons an atom of an element has. It is the basis of the arranegement of the periodic table and has taken the scientific world a long time to discover. About 1860 C. E. Mendeleyev published the first such table.
What atoms with same atomic number but different atomic masses?
Isotopes of the same element have the same number of protons (atomic number) but differ in number of neutrons (hence atomic masses).
Si units used for the masses of atomic particles?
The Si unit used for the masses of particles is the atomic mass unit (amu).
How are isotopes related to atomic masses not being whole numbers?
Atomic masses are the weighted average of all the isotopes of an element. The average is based on the relative abundance of each isotope. Let say we have an element with two isotopes, the first isotope has a mass of 6 and the second has a mass of 8. If we took a straight average of the atomic masses then the element would have a mass of 7. But a weighted average based on the abundance of each isotope would be different (unless both isotopes are found to be in equal amounts ie. both 50% abundance) If the isotope with a mass of 6 had a relative abundance of 75% (meaning that 3/4 of all atoms of that element had a mass of 6) then the other isotope would have a relative abundance of 25% (relative abundance must add up to 100%). The atomic mass of the elements would be calculated by multiplying each isotopes mass my the relative abundance and then adding the two results together. 75% (6) = 4.5 25% (8) = 2.0 4.5 + 2.0 = 6.5 The atomic mass for this element would have an atomic mass of 6.5 amu (atomic mass units)
How did Mendeleev arrange chemical elements?
He arranged the elements in the increasing order of their atomic masses and repeating periodic properties.
How do atomic numbers and atomic masses increase in the periodic table?
The atomic number and atomic masses increase as you move from left to right.
How are the atomic numbers and the atomic masses of the elements related to how the elements are arranged on peridoic table?
Elements are arranged in a periodic table by atomic number, lower on top and left. Atomic masses have no direct relationship to the arrangement of atoms, although generally atoms with higher atomic numbers will have higher atomic masses. (There are at least three exceptions for atoms with atomic numbers differing by 1.)
What elements have such small masses that they are not even considered when atomic masses are calculated?
Electrons
Why don27t elements in the periodic table have whole numbers for their atomic masses?
Because the masses of protons, neutrons and electrons are not whole numbers.
Which statement best explains why most atomic masses on the periodric table are decimal numbers?
Atomic masses are a weighted average of the naturally occurring isotopes.
Why the atomic mass numbers listed for elements on the Periodic Table are not whole numbers.?
Why are atomic masses of elements not generally whole numbers? The atomic masses listed on the periodic table are a weighted AVERAGE of an element'sisotopes. ... An element's atomic number is the number of protons in its nucleus. Number of protons specifies atom type.
Why aren't atomic masses of elements not whole numbers?
because of its no. in table of elements
Why is the relative atomic mass of chloride not a whole number?
Because relitive atomic masses are NEVER whole numbers.
What are atoms of the same element thay have different atomic masses?
when you have two different forms of an atom with different masses, it's called an isotope of the atom.
What cause different isotopes to have different atomic masses?
Different numbers of neutrons in their nuclei.
How do you get atomic mass?
Atomic mass is found by adding together the individual masses of the numbers of protons, neutrons, and electrons in the atom.--> Atomic Mass = protons + neutrons
Why was basis of classification of element in the periodic table changed from atomic mass to atomic number?
Mendeleev's periodic table was based on the atomic masses of elements. However, this was not effective when isotopes were discovered. An isotope of an element is defined as the element having the same atomic number but varying mass numbers. So, mass numbers weren't constant and hence, a better characteristic was chosen -atomic number. Atomic number of any element was a characteristic of a particular element. Hence atomic numbers were taken as the basis of classification instead of atomic masses.
