Question 1

Which experiment led to the discovery that atoms contain a small, dense nucleus?

Accepted Answer

Rutherford's gold foil experiment

Question 2

According to Rutherford’s nuclear theory, where are most of the atom’s mass and all its positive charge located?

Accepted Answer

In the nucleus

Question 3

Which of the following statements about isotopes is correct?

Accepted Answer

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

Question 4

An atom of calcium-44 ($$^{44}_{20}\mathrm{Ca}^{2+}) $$has how many electrons?

Accepted Answer

18

Question 5

Which subatomic particle has a relative charge of $$+1$$ and is found in the nucleus?

Accepted Answer

Proton

Question 6

A neutral atom of neon-22 ($$^{22}_{10}\mathrm{Ne}) $$contains how many neutrons?

Accepted Answer

12

Question 7

Which of the following best describes the plum pudding model of the atom?

Accepted Answer

Electrons embedded in a sphere of positive charge

Question 8

How many electrons are present in an $$\mathrm{O}^{2-}$$ ion?

Accepted Answer

10

Question 9

Which of the following is true for all neutral atoms?

Accepted Answer

The number of electrons equals the number of protons.

Question 10

An isotope of argon has an atomic number of 18 and a mass number of 40. How many neutrons does it contain?

Accepted Answer

20

Question 11

Which of the following ions has more electrons than protons?

Accepted Answer

$$\mathrm{O}^{2-}$$

Question 12

If an atom has 15 protons, 16 neutrons, and 18 electrons, what is its charge?

Accepted Answer

$$3-$$

Question 13

Which statement best explains why most alpha particles passed straight through the gold foil in Rutherford’s experiment?

Accepted Answer

The gold atoms are mostly empty space.

Question 14

What is the mass number ($$A) of an $$atom with 17 protons and 20 neutrons?

Accepted Answer

$$A = 37$$

Question 15

Which of the following is NOT a property shared by all isotopes of a given element?

Accepted Answer

Number of neutrons

Question 16

A neutral atom of $$^{16}_{8}\mathrm{O}$$ has how many protons, neutrons, and electrons?

Accepted Answer

8 protons, 8 neutrons, 8 electrons

Question 17

Which of the following best describes a cation?

Accepted Answer

An atom that has lost electrons

Question 18

Which of the following particles has the smallest mass?

Accepted Answer

Electron

Question 19

If an atom has an atomic number $$Z = 11$$ and a mass number $$A = 23$$, how many neutrons does it have?

Accepted Answer

12

Question 20

Which of the following statements about neutrons is correct?

Accepted Answer

Neutrons have nearly the same mass as protons.

Atoms and Elements: Structure, Subatomic Particles, Isotopes, and Ions

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