Q. 4.51 - An Introduction to General, Organic, and Biological Chemistry

Question

Identify the elements that have following electron arrangements:

Step-by-Step Solution

Answer

Our required elements are:

(a) Lithium 

(b) Magnesium 

(c) Hydrogen

(d) Chlorine

(e) Oxygen

Part	Element	Energy Levels
		$1$	$2$	$3$
a	Lithium	$2$	$1$
b	Magnesium	$2$	$8$	$2$
c	Hydrogen	$1$
d	Chlorine	$2$	$8$	$7$
e	Oxygen	$2$	$6$

Part (a) Step 1: Given information

We need to identify element with electron arrangement: 

Energy Level
$1$	$2$	$3$
$2$	$1$

Part (a) Step 2: Explanation

Element having atomic number $3$ with $2$ electrons in $1^{st}$ energy level  and $1$ electron in $2^{nd}$ energy level  is lithium.

Hence, element is lithium.

Part (b) Step 1: Given information

We need to identify element with electron arrangement: 

Energy Level
$1$	$2$	$3$
$2$	$8$	$2$

Part (b) Step 2: Explanation

Element having atomic number $12$ with $2$ electrons  in $1^{st}$energy level , $8$  electron in $2^{nd}$ energy level , and $2$ electron in $3^{rd}$energy level  is magnesium.

Hence, element is magnesium.

Part (c) Step 1: Given information

We need to identify element with electron arrangement: 

Energy Level
$1$	$2$	$3$
$1$

Part (c) Step 2: Explanation

Element having atomic number $1$and $1$ electron in $1^{st}$ energy level  is hydrogen.

Hence, element is hydrogen.

Part (d) Step 1: Given information

We need to identify element with electron arrangement: 

Energy Level
$1$	$2$	$3$
$2$	$8$	$7$

Part (d) Step 2: Explanation

Element having atomic number $17$  with $2$electrons  in $1^{st}$energy level , $8$electrons in $2^{nd}$ energy level , and $7$ electron in $3^{rd}$ energy level is chlorine.

Hence, element is chlorine. 

Part(e) Step 1: Given information

We need to identify element with electron arrangement: 

Energy Level
$1$	$2$	$3$
$2$	$6$

Part (e) Step 2: Explanation

Element having atomic number $8$  with $2$ electrons in $1^{st}$ energy level and $6$ electron in $2^{nd}$energy level is oxygen .

Hence, element is oxygen.