Question

From the table given below answer the following questions-
Element A B C D E
Mass number 11 19 4 23 9
Atomic number 5 9 2 11 4
a) how many electrons are present in E
b) which among the above is an inert gas and why
c) which will form negatively changed ion
d) which element has 12 neutrons and why
e) which atom will form cation with one positive charge

Answer 1

a. 4

b. C since it has fully filled outermost shell.

c. B

d.D since ot has 11 protons and the sum of proton and neutron is the atomic mass of the element so 23-11=12

e. D

Answer 2

a) Electrons present in E are 4

b) Element C is an inert gas

c) Element B forms negatively changed ion

d) Element D has 12 neutrons

e) Element D will form cation with one positive charge

Explanation:

Electronic configuration represents the total number of electrons that a neutral element contains. We add all the superscripts to know the number of electrons in an atom.

Atomic number is defined as the number of protons or the number of electrons that are present in an electrically neutral atom.

Atomic number = Number of protons = number of electrons

Mass number is defined as the sum of number of protons and neutrons that are present in an atom.

Mass number = Number of protons + Number of neutrons

The electrons are filled according to Afbau's rule in order of increasing energies.

A= $B:5:1s^22s^22p^1$

B= $F:9:1s^22s^22p^5$

C= $He:2:1s^2$

D= $Na:11:1s^22s^22p^63s^1$

E = $Be:4:1s^22s^2$

a) Thus there are 4 electrons in E as atomic number is 4.

b) Inert gases have complete duplet or octet. As element C has complete duplet, it is an inert gas

c) As element B has one electron less than nearest stable inert gas neon , it can readily accept electrons and thus form negatively charged ion.

$F^-:10:1s^22s^22p^6$

d) Mass number is defined as the sum of number of protons and neutrons that are present in an atom.

23 = 11 + Number of neutrons  (for D)

Number of neutrons  = 12

e) As element D has one electron more than nearest stable inert gas neon , it can readily lose electrons and thus form positively charged ion.

$Na^+:10:1s^22s^22p^6$

Learn more about electronic configuration

https://brainly.in/question/5863369

https://brainly.in/question/7529010