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from JAWAHAR CENTRAL SCHOOL, asked a question
Subject: Science , asked on 24/1/12

Differences between Mendeleev 's and Moseley 's periodic law?

Mendeeleve’s periodic table “ The properties of the elements are a periodic functon of their atomic weights”. Following are the properties

1. The elements, if arranged according to their atomic weights, exhibit an evident stepwise variationof properties.
2. Chemically analogous elements have either similar atomic weights (Pt, Ir, Os), or weights which increase by equal increments (K, Rb, Cs).
3. The arrangement according to atomic weight corresponds to the valence of the element and to a certain extent the difference in chemical behavior, for example Li, Be, B, C, N, O, F.
4. The elements distributed most widely in nature have small atomic weights, and all such elements are marked by the distinctness of their behavior. They are, therefore, the representative elements; and so the lightest element H is rightly chosen as the most representative.
5. The magnitude of the atomic weight determines the properties of the element. Therefore, in the study of compounds, not only the quantities and properties of the elements and their reciprocal behavior is to be taken into consideration, but also the atomic weight of the elements. One can predict the discovery of many new elements, for example analogues of Si and Al with atomic weights of 65-75.
6. A few atomic weights will probably require correction; for example Te cannot have the atomic weight 128, but rather 123-126.

Mosely Law: Henry Moseley discovered that the wavelength (energy) of an X-ray depended upon the nuclear charge of an atom. Moseley's Law describes the relationship between atomic number and wavelength of a spectral line:

The constant σ (sigma) is equal to 1 for the K-lines and 7.4 for the more shielded L-lines. For energy this expression is approximately equivalent to:

Moseley's determination of this relationship provided a simple test of the order of the elements according to Z. Where Z denote atomic number of an element.

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Hi,

I agree with both of your friends...........

• 1

mendeleev 's periodic law ws based on atomic masses

n as it stated

' 'the properties of elements are the periodic function of their atomic masses ' '

whereas

moseley 's periodic law ws based on atomic numbers

n as it stated

' ' the properties of elemnets r the periodic function of their atomic numbers ' '

hope i helped... :))

• 1

in mendelleevs periodic table ,the mendeleevs  periodic law states that properties of elements r periodic functions of their at mass

modern law states that prpperties of elements r periodic fun of at nos

if u want more give a thumb up there r 6 more difference 2 come......

this is not copy-paste