Question

Use the Gizmo to answer the following questions.
A. How many electrons are in a neutral atom of lithium? ___________
B. How many neutrons are in an atom of Mg-25? ___________
C. What is the mass number of an atom with 5 protons and 7 neutrons? ________
D. An ion is a charged atom. How many electrons are in O2- ? ___________
E. How many electrons are in Mg2+?

Answer 1

Answer:

a. 3 electrons

b. 13 neutrons

c. 12 mass number

d. 10 electrons

e. 10 electrons

Explanation:

A. For an element , the atomic number of a given element is equal to the number of protons , and

For a neutral atom , the number of electrons equals the number of protons ,

Hence ,

The atomic number of Li = 3 ,

Hence ,

Number of electron for Li = 3 .

B.

Number of neutrons = mass number - atomic number ,

For Mg-25

For Magnesium , atomic number = 12 ,

Number of neutrons = 25 - 12 = 13 neutrons

C. Mass number of an element is equal to the sum of number of protons and number of neutrons ,

Hence , mass number = 5 + 7 = 12 .

D. For a negatively charged ion , add the negative charge value with the number of electrons of the neutral atom ,

For Oxygen , atomic mass = 8 ,

hence , number of electrons = 8

For O²⁻ = 8 + 2 = 10 electrons

E. For a positively charged ion , subtract the positive charge value with the number of electrons of the neutral atom ,

For Magnesium , atomic number = 12 ,

hence , number of electrons = 12 ,

for ,  Mg²⁺ , number of electrons = 12 - 2 = 10 electrons ,