Question

1. how many total electrons does k have?

a. 17
b. 18
c. 19
d. 20

1. how many total electrons does f have?

a. 9
b. 10
c. 11
d. 8

1. how many total electrons does ne have?

a. 9
b. 10
c. 11
d. 8

1. what is the mass number for be?

your answer

Explanation:

Step1: Recall atomic number and electron - count relation

In a neutral atom, the number of electrons is equal to the atomic number.

Step2: Find atomic number of K

The atomic number of potassium (K) is 19. So, it has 19 electrons.

Step3: Find atomic number of F

The atomic number of fluorine (F) is 9. So, it has 9 electrons.

Step4: Find atomic number of Ne

The atomic number of neon (Ne) is 10. So, it has 10 electrons.

Step5: Find mass number of Be

The mass number of beryllium (Be) is 9 (from the periodic - table).

Answer:

1. C. 19
2. A. 9
3. B. 10
4. 9