Q: Which of the following is the correct formula to calculate the number of neutrons in an atom?

$$\text{Number of neutrons} = \text{Mass number} - \text{Atomic number}$$

Question 1

Which of the following statements best describes an element?

Accepted Answer

An element is a pure substance that cannot be broken down into simpler substances by chemical means.

Question 2

Which of the following elements is a halogen and what is its group number?

Accepted Answer

Chlorine (Cl), Group 7A

Question 3

A neutral atom of aluminum has an atomic number of 13. How many electrons does it have?

Accepted Answer

$$13$$

Question 4

Which of the following best explains why the atomic size increases as you move down a group in the periodic table?

Accepted Answer

The number of energy levels increases, placing valence electrons farther from the nucleus.

Question 5

Which of the following is the correct electron configuration for sulfur (S)?

Accepted Answer

$$1s^22s^22$p^63s^23$p^4$$

Question 6

A sample of chlorine contains two isotopes: $$^{35}\mathrm{Cl} (75.76$$% abundance, mass = 34.97 amu) and $$^{37}\mathrm{Cl} (24.24$$% abundance, mass = 36.97 amu). What is the atomic mass of chlorine?

Accepted Answer

$$35.45$$ amu

Question 7

Which subatomic particle is found outside the nucleus and has a negative charge?

Accepted Answer

Electron

Question 8

Which element is most likely to have the highest ionization energy?

Accepted Answer

Chlorine (Cl)

Question 9

A neutral atom of lead (Pb) has a mass number of 207 and an atomic number of 82. How many neutrons does it have?

Accepted Answer

$$207 - 82 = 125$$ neutrons

Question 10

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 11

Which of the following elements is a metal, based on its position in the periodic table?

Accepted Answer

Magnesium (Mg)

Question 12

What is the maximum number of electrons that can occupy the third energy level ($$n=3) of an $$atom?

Accepted Answer

$$18$$

Question 13

Which of the following best describes the trend in metallic character across a period from left to right?

Accepted Answer

Metallic character decreases.

Question 14

A farmer is applying a fertilizer containing potassium (K). Which group does potassium belong to, and what is a characteristic property of this group?

Accepted Answer

Group 1A; highly reactive with water

Question 15

Which of the following electron configurations represents a noble gas?

Accepted Answer

$$1s^22s^22$p^63s^23$p^6$$

Question 16

Which of the following is the correct formula to calculate the number of neutrons in an atom?

Accepted Answer

$$	ext{Number of neutrons} = 	ext{Mass number} - 	ext{Atomic number}$$

Question 17

Which of the following elements is most likely to be found as a major component in the human body?

Accepted Answer

Oxygen (O)

Question 18

Which of the following best describes the arrangement of electrons in the shells and subshells for a calcium (Ca) atom?

Accepted Answer

$$1s^22s^22$p^63s^23$p^64s^2$

Question 19

Which of the following is a correct statement about the periodic law?

Accepted Answer

Elements are arranged in order of increasing atomic number.

Atoms and Elements: Structure, Properties, and Periodic Trends

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