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 is the correct chemical symbol for gold, and what is its origin?

Accepted Answer

Au, from the Latin word 'aurum'

Question 3

Which of the following elements is a metalloid?

Accepted Answer

Silicon

Question 4

A student is given a sample of an unknown element. It is shiny, conducts electricity well, and is malleable. Based on these properties, to which class does this element most likely belong?

Accepted Answer

Metal

Question 5

Which of the following best describes the difference between a group and a period in the periodic table?

Accepted Answer

A group is a vertical column; a period is a horizontal row.

Question 6

Which of the following elements is located in Group 2A (2), Period 3 of the periodic table?

Accepted Answer

Magnesium

Question 7

According to Dalton's atomic theory, which statement is correct?

Accepted Answer

Atoms of different elements combine to form compounds.

Question 8

Which subatomic particle has a positive charge?

Accepted Answer

Proton

Question 9

Rutherford's gold foil experiment led to which major discovery about atomic structure?

Accepted Answer

Atoms have a small, dense, positively charged nucleus.

Question 10

An atom of aluminum has 13 protons and 14 neutrons. What is its mass number?

Accepted Answer

$$27$$

Question 11

Which of the following is true for a neutral atom?

Accepted Answer

The number of protons equals the number of electrons.

Question 12

A certain isotope of oxygen is represented as $$^{18}_{8}\mathrm{O}. $$How many neutrons does this isotope have?

Accepted Answer

$$10$$

Question 13

Which of the following pairs are isotopes of the same element?

Accepted Answer

$$^{14}_{6}\mathrm{C}$$ and $$^{12}_{6}\mathrm{C}$$

Question 14

If an atom has an atomic number of $$20$$ and a mass number of $$40$$, how many neutrons does it have?

Accepted Answer

$$20$$

Question 15

Which of the following best explains why metalloids are used in semiconductors?

Accepted Answer

They have properties intermediate between metals and nonmetals, allowing them to control electrical conductivity.

Question 16

A patient is diagnosed with anemia due to a deficiency of an element essential for oxygen transport in blood. Which element is most likely deficient?

Accepted Answer

Iron

Question 17

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 18

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 19

A neutral atom of sodium ($$^{23}_{11}\mathrm{Na}) $$has how many electrons?

Accepted Answer

$$11$$

Question 20

Which of the following best describes the location of nonmetals on the periodic table?

Accepted Answer

Nonmetals are located to the right of the heavy zigzag line.

Elements, Atomic Structure, and the Periodic Table: GOB Chemistry Study Notes (Week 2)

Guida di studio - Domande di pratica

Study guide - Flashcard