Question 1

Which scientist is most closely associated with the development of modern atomic theory, as referenced in early ideas of atomic theory?

Accepted Answer

John Dalton

Question 2

According to Dalton’s Atomic Theory, which statement is correct regarding elements?

Accepted Answer

Elements are made of only one type of atom.

Question 3

Dalton’s Atomic Theory states that compounds have fixed ratios. Which of the following best illustrates this concept?

Accepted Answer

Sodium chloride always has a 1:1 ratio of Na to Cl.

Question 4

Which of the following is NOT a postulate of Dalton’s Atomic Theory?

Accepted Answer

Atoms can be created or destroyed in chemical reactions.

Question 5

If a compound is formed from sodium and chlorine, what is the chemical formula and what does Dalton’s theory say about its ratio?

Accepted Answer

NaCl; the ratio of Na to Cl is always 1:1

Question 6

Which statement best describes the difference between atoms, molecules, and ions?

Accepted Answer

Atoms are single units, molecules are combinations of atoms, ions are charged particles.

Question 7

Dalton’s Atomic Theory states that atoms of the same element are identical. Which real-world observation challenges this postulate?

Accepted Answer

The existence of isotopes.

Question 8

Which equation represents the law of constant composition as described by Dalton’s Atomic Theory?

Accepted Answer

$$\mathrm{H_2O}$$ always contains 2 parts hydrogen and 1 part oxygen by mass.

Question 9

Which of the following best explains why elements have different properties according to Dalton’s Atomic Theory?

Accepted Answer

Elements have different types of atoms.

Question 10

A student mixes sodium and chlorine in a 2:1 ratio. According to Dalton’s Atomic Theory, what will be the result?

Accepted Answer

Only NaCl will form, and excess sodium will remain.

Question 11

Which of the following is a direct consequence of Dalton’s postulate that compounds have fixed ratios?

Accepted Answer

The mass ratio of elements in a compound is always the same.

Question 12

Which statement about molecules is consistent with Dalton’s Atomic Theory?

Accepted Answer

Molecules are made of atoms bonded together in fixed ratios.

Question 13

Which of the following is an example of a molecule?

Accepted Answer

$$\mathrm{O_2$}$$

Question 14

Dalton’s Atomic Theory helped explain which law of chemistry?

Accepted Answer

Law of Constant Composition

Question 15

Which of the following is a correct statement about ions?

Accepted Answer

Ions are atoms or molecules that have gained or lost electrons.

Atoms, Molecules, and Ions: Foundations of Atomic Theory

Study Guide - Practice Questions