Question

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Answer 1

in the periodic table, elements are classified in the ascending order of their atomic numbers. atomic number is the number of protons

in elements the number of protons is equal to the number of electrons

the condensed notation of electron configuration is when the symbol of the noble gas closest to the elements electron configuration is mentioned.

[He] 2s² - number of electrons in He is 2 , and 2 more electrons in the s subshell adds upto a sum of 4 electrons. number of protons = number of electrons

then number of protons = 4

then atomic number is 4. element with atomic number 4 is Be

the element is Be

[Ne] 3s² 3p⁵

Ne atomic number is 10. 10 + 7 electrons in the third shell = 17 electrons in total

atomic number - 17 is Cl

element is Cl

[Xe] 6s¹

Xe atomic number is 54, 54 + 1 electron in the sixth shell = 55 electrons in total

atomic number of 55 is Cs

element is Cs

[Ar] 4s² 3d⁹

Ar atomic number is 18. 18 + 2 electrons in 4th shell and 9 in d subshell of 3rd shell = 29 electrons in total

atomic number of 29 is Cu

element is Cu

Answer 2

[He]2s2: Be
[Ne]3s23p5: Cl
[Xe]6s1: Cs
[Ar]4s23d9: Cu