Atmos of given elements will have the same mass true or false .

True because,

Atoms of different elements have different masses because different atoms have a different number of subatomic particles i.e neutrons, protons and electrons.

Atomic mass of an element cannot be same as the mass of a single atom of that element because by investigation of mass spectrometry it was found that many naturally occurring elements exist in the form of two or more isotopes. Isotopes are the atoms of the same elements having the same atomic number containing the same number of protons but the different number of neutrons and because of this, it possesses different mass number. So, the observed atomic mass of the atom of an element is the average atomic mass of the elements. Average of masses of a different isotope of the same element is taken and then the atomic mass of the element is decided.

A formula to calculate average atomic mass:-

Example:-

Lithium exists in nature in the form of two isotopes Li−6 and Li−7 with atomic masses 6.0151u and 7.0160u and the percentages 7.59 and 92.41 respectively.

Solution:- Average atomic mass of Li

[Atomic mass of Li−6× percentage + Atomic mass of Li−7× percentage]/100

=

100

6.015u×7.59+7.0160u×92.41

=6.939u

Hence, the atomic mass of an element is not the same as the mass of a single atom of that element; Atomic mass is average of isotopic mass o atoms.

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.

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