Q: Which of the following correctly describes how to determine the number of neutrons in an atom?

Subtract the atomic number from the mass number: $$\text{Neutrons} = \text{Mass Number} - \text{Atomic Number}$$

Q: Which of the following is the correct formula to find the number of protons in an atom?

$$\text{Protons} = \text{Atomic Number}$$

Question 1

Which of the following correctly describes how to determine the number of neutrons in an atom?

Accepted Answer

Subtract the atomic number from the mass number: $$	ext{Neutrons} = 	ext{Mass Number} - 	ext{Atomic Number}$$

Question 2

An atom of chromium has a mass number of 52 and an atomic number of 24. How many neutrons does it have?

Accepted Answer

$$52 - 24 = 28$$ neutrons

Question 3

If a neutral atom has 15 electrons, what is its atomic number?

Accepted Answer

15

Question 4

Which of the following statements about protons and electrons in a neutral atom is correct?

Accepted Answer

The number of protons equals the number of electrons.

Question 5

A certain element has 20 protons, 20 neutrons, and 18 electrons. What is the charge of this atom?

Accepted Answer

$$+2$$

Question 6

Which of the following best explains why isotopes of the same element have different mass numbers?

Accepted Answer

They have different numbers of neutrons.

Question 7

A hospital uses a chromium isotope with a mass number of 53 for diagnostic imaging. If the atomic number of chromium is 24, how many neutrons are in this isotope?

Accepted Answer

$$53 - 24 = 29$$ neutrons

Question 8

Which of the following is true for all atoms of a given element?

Accepted Answer

They have the same number of protons.

Question 9

A sample contains two isotopes of chromium: one with 28 neutrons and one with 29 neutrons. Both have 24 protons. What are the mass numbers of these isotopes?

Accepted Answer

52 and 53

Question 10

A patient receives an injection of a neutral atom with 17 protons and 18 neutrons. What is the atomic number and mass number of this atom?

Accepted Answer

Atomic number: 17, Mass number: 35

Question 11

Which of the following best describes the relationship between atomic number and the identity of an element?

Accepted Answer

The atomic number determines the identity of the element because it equals the number of protons.

Question 12

A neutral atom of an unknown element has a mass number of 40 and 18 electrons. What is the number of neutrons in this atom if its atomic number is 18?

Accepted Answer

$$40 - 18 = 22$$ neutrons

Question 13

Which of the following is the correct formula to find the number of protons in an atom?

Accepted Answer

$$	ext{Protons} = 	ext{Atomic Number}$$

Question 14

A certain ion has 16 protons, 18 electrons, and 16 neutrons. What is the charge of this ion?

Accepted Answer

$$-2$$

Question 15

Which of the following statements is true regarding the mass number of an atom?

Accepted Answer

The mass number is the sum of protons and neutrons.

Question 16

A medical technologist is analyzing a sample and finds an atom with 19 protons, 20 neutrons, and 18 electrons. What is the net charge of this atom?

Accepted Answer

$$+1$$

Question 17

Which of the following is a correct statement about electrons in a neutral atom?

Accepted Answer

The number of electrons equals the number of protons.

Question 18

A sample of an element contains atoms with 12 protons, 12 neutrons, and 10 electrons. What is the symbol and charge of this ion?

Accepted Answer

$$	ext{Mg}^{2+}$$

Question 19

Which of the following best explains why the mass number is not found on the periodic table?

Accepted Answer

Because the periodic table lists the average atomic mass, not the mass number of individual isotopes.

Question 20

A patient is given a dose of a chromium isotope with 24 protons and 28 neutrons. What is the isotope's mass number and how is it written in isotope notation?

Accepted Answer

Mass number: 52; Isotope notation: $$^{52}	ext{Cr}$$

Atoms, Protons, Neutrons, and Electrons: Basic Atomic Structure

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