Question

1. complete the table for the following elements.

element number of protons number of electrons number of neutrons atomic number mass number
manganese 25 25 30 25
sodium 11 11 12 11
bromine 35 45
yttrium 39 39 39 89
arsenic 33 33 33 75
actinium 227
chapter 4 atomic structure 89

Explanation:

Step1: Recall mass - number formula

The mass number ($A$) of an atom is the sum of the number of protons ($p$) and the number of neutrons ($n$), i.e., $A=p + n$. The atomic number ($Z$) is equal to the number of protons. In a neutral atom, the number of electrons is equal to the number of protons.

Step2: Calculate mass number for Manganese

For Manganese, $p = 23$, $n=30$. Using the formula $A=p + n$, we have $A=23 + 30=53$.

Step3: Calculate mass number for Sodium

For Sodium, $p = 11$, $n = 12$. Then $A=11+12 = 23$.

Step4: Calculate number of electrons for Bromine

In a neutral atom, the number of electrons is equal to the number of protons. For Bromine, $p = 35$, so the number of electrons is 35. And the atomic number $Z = 35$, and using $A=p + n$ with $p = 35$ and $n = 45$, we get $A=35 + 45=80$.

Step5: Calculate number of neutrons for Yttrium

Given $A = 89$ and $p=39$, using $A=p + n$, we can find $n=A - p=89 - 39 = 50$.

Step6: Calculate number of neutrons for Arsenic

Given $A = 75$ and $p = 33$, using $A=p + n$, we find $n=A - p=75 - 33=42$.

Step7: Calculate number of protons, electrons and neutrons for Actinium

The atomic number of Actinium is 89. So $p=89$, in a neutral atom $e = 89$. Given $A = 227$, using $A=p + n$, we get $n=A - p=227-89 = 138$.

Element	Number of Protons	Number of Electrons	Number of Neutrons	Atomic Number	Mass Number
Sodium	11	11	12	11	23
Bromine	35	35	45	35	80
Yttrium	39	39	50	39	89
Arsenic	33	33	42	33	75
Actinium	89	89	138	89	227

Answer:

Element	Number of Protons	Number of Electrons	Number of Neutrons	Atomic Number	Mass Number
Sodium	11	11	12	11	23
Bromine	35	35	45	35	80
Yttrium	39	39	50	39	89
Arsenic	33	33	42	33	75
Actinium	89	89	138	89	227