A Quiz On Atomic Theory: Trivia Quiz!

1. Phosphorus: protons neutrons electrons

11 12 10

1 0 2

15 16 15

20 20 18

The atomic number is 15, which means phosphorus has 15 protons. The mass number is 31, which is the sum of protons plus neutrons. 31 - 15 = 16 neutrons. Because a neutral atom has equal numbers of protons and electrons, phosphorus also has 15 electrons.

Explanation

The atomic number is 15, which means phosphorus has 15 protons. The mass number is 31, which is the sum of protons plus neutrons. 31 - 15 = 16 neutrons. Because a neutral atom has equal numbers of protons and electrons, phosphorus also has 15 electrons.

2. What scientist was the first to conclude through experimentation that atoms have positive charges in their nuclei?

Bohr

Balton

Mosley

Rutherford

Rutherford discovered that atoms have a dense, positively charged nucleus through the gold foil experiment.

Explanation

Rutherford discovered that atoms have a dense, positively charged nucleus through the gold foil experiment.

3. How many protons, neutrons, and electrons are in a neutral atom of sodium?

11 p+, 12 n0, 11 e-

11 p+, 11 n0, 12 e-

12 p+, 11 n0, 12 e-

12 p+, 11 n0, 11 e-

Sodium has an atomic number of 11, which means it has 11 protons. If the atom is neutral, it has equal numbers of protons and electrons. The mass number of sodium is 23; mass number - atomic number = neutrons. 23 - 11 = 12 neutrons

Explanation

Sodium has an atomic number of 11, which means it has 11 protons. If the atom is neutral, it has equal numbers of protons and electrons. The mass number of sodium is 23; mass number - atomic number = neutrons. 23 - 11 = 12 neutrons

4. An increase in atomic number is related to an increase in atomic mass because -

More electrons are present in the atomic nucleus

More electrons are orbiting the atomic nucleus

More protons are present in the atomic nucleus

More protons are orbiting the atomic nucleus

If the atomic number has increased, that means protons have been added. Protons are located in the nucleus and have mass.

Explanation

If the atomic number has increased, that means protons have been added. Protons are located in the nucleus and have mass.

5. Isotopes of an element have different -

Atomic numbers

Mass numbers

Numbers of protons

Numbers of outer-shell electrons

Isotopes of an element have different numbers of neutrons. The mass number is equal to the sum of the number of protons plus neutrons in the atom. If neutrons differ between atoms, mass number also differs.

Explanation

Isotopes of an element have different numbers of neutrons. The mass number is equal to the sum of the number of protons plus neutrons in the atom. If neutrons differ between atoms, mass number also differs.

6. Atoms of the same element must

Contain the same number of neutrons

Have the same mass number

Contain the same number of protons

Have equal numbers of protons and neutrons

Atoms of the same element have the same atomic number (given on the periodic table), which is equal to the number of protons.

Explanation

Atoms of the same element have the same atomic number (given on the periodic table), which is equal to the number of protons.

7. Which of these conclusions can be drawn from Rutherford's experiment?

Each atom contains electrons.

The nucleus of an atom can be split.

Each atom contains protons.

Atoms are mostly empty space.

Rutherford's experiment involved firing alpha particles at a thin sheet of gold foil. He observed that most of the alpha particles passed through the foil without any deflection, while a small fraction were deflected at large angles. This led him to conclude that atoms are mostly empty space, with a tiny, dense nucleus at the center where most of the mass is concentrated. The fact that most of the alpha particles passed through the foil without being deflected indicated that atoms do not contain electrons, protons, or a nucleus that can be split.

Explanation

Rutherford's experiment involved firing alpha particles at a thin sheet of gold foil. He observed that most of the alpha particles passed through the foil without any deflection, while a small fraction were deflected at large angles. This led him to conclude that atoms are mostly empty space, with a tiny, dense nucleus at the center where most of the mass is concentrated. The fact that most of the alpha particles passed through the foil without being deflected indicated that atoms do not contain electrons, protons, or a nucleus that can be split.

8. How does the radioactive isotope of C-14 differ from its stable counterpart C-12?

It has a different number of protons and two less neutrons than C-12.

It has the same number of protons and two more electrons than C-12.

It has the same number of protons but two more neutrons than C-12.

It has a different number of protons and two more neutrons than C-12.

Isotopes are atoms of the same element with different numbers of neutrons. This means that the atomic number (number of protons) is the same, but the mass number differs. Mass number is simply the sum of protons plus neutrons. Therefore, since protons are the same in C-12 and C-14, C-14 must have two more neutrons than C-12.

Explanation

Isotopes are atoms of the same element with different numbers of neutrons. This means that the atomic number (number of protons) is the same, but the mass number differs. Mass number is simply the sum of protons plus neutrons. Therefore, since protons are the same in C-12 and C-14, C-14 must have two more neutrons than C-12.

9. Radioactive iodine-131 has a half-life of eight days. The amount of a 200.0 gram sample left after 32 days would be

6.25 g

12.5 g

25.0 g

50.0 g

Each half life is eight days. In thirty two days, there are four half lives. As each half-life occurs, the amount of iodine-131 decreases by half. After dividing 200.0 g by 2 four times, the amount left is 12.5 g.

Explanation

Each half life is eight days. In thirty two days, there are four half lives. As each half-life occurs, the amount of iodine-131 decreases by half. After dividing 200.0 g by 2 four times, the amount left is 12.5 g.