The atomic number of lithium is 3. how many neutrons does an atom of lithium have if it is represented by the symbol shown below?

7li
a. 2 neutrons
b. 13 neutrons
c. 4 neutrons
d. 7 neutrons

C. 4 neutrons

Explanation:

General representation of an element is given as:  

where,

Z represents Atomic number

A represents Mass number

X represents the symbol of an element

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

A = Mass number = Number of protons + Number of neutrons = 7

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

Z= Atomic number = Number of electrons = Number of protons = 3

7 = 3 + Number of neutrons

Number of neutrons  = 4

Thus there are 4 neutrons.

each chemical family is represented as a group or column on the periodic table. based on chemical properties, there are 6 types of chemical families. group 1 represents alkali metals, group 2 represents alkaline earth metals, groups 3 to 12 represent transition metals, groups 13 to 16 represent non-metals and other metals, group 17 represents halogens and group 18 represents noble gases.

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hienas tends to steal pray from other animals. crows and vultures tend to eat dead animals and leftovers.

hope it ,

bioteacher101