1 amu is defined as $$1.660539 \times 10$$^{-24}$$\ \mathrm{g}$$ and is based on the mass of a carbon-12 atom.

Question 1

Which statement best describes the main difference between the atomic model proposed in 1911 and the one proposed in 1913, as shown in the image?

Accepted Answer

The 1911 model introduced the concept of a nucleus, while the 1913 model added quantized electron orbits.

Question 2

Which of the following statements about atomic orbitals is correct based on the images and your knowledge of quantum mechanics?

Accepted Answer

s orbitals are spherical, while p orbitals are roughly dumbbell-shaped.

Question 3

Which atomic model first introduced the idea that electrons occupy specific energy levels or orbits around the nucleus?

Accepted Answer

The Bohr model (1913)

Question 4

Which subatomic particle is responsible for the majority of an atom's volume?

Accepted Answer

Electrons

Question 5

What is the charge and approximate mass (relative to a proton) of an electron?

Accepted Answer

Charge: $$-1$$, Mass: $$\frac{1}{1836} of a $$proton

Question 6

Which unit would be most appropriate for describing the length of a chemical bond in a small molecule?

Accepted Answer

Angstrom ($$1\ \mathrm{\AA} = 10$$^{-10}$$\ \mathrm{m})$$

Question 7

Which of the following best explains why electrons occupy a large volume around the nucleus?

Accepted Answer

Electrons repel each other and are attracted to the nucleus, resulting in a large electron cloud.

Question 8

Which statement about the atomic mass unit (amu) is correct?

Accepted Answer

1 amu is defined as $$1.660539 	imes 10$$^{-24}$$\ \mathrm{g}$$ and is based on the mass of a carbon-12 atom.

Question 9

Which of the following is NOT a postulate of Dalton’s atomic theory?

Accepted Answer

Atoms can be divided into protons, neutrons, and electrons.

Question 10

A protein has a mass of 50,000 Da. What is its mass in kilodaltons (kDa)?

Accepted Answer

$$50\ \mathrm{kDa}$$

Question 11

Which of the following best describes the relationship between protons and electrons in a neutral atom?

Accepted Answer

The number of protons equals the number of electrons.

Question 12

Which of the following statements about electric charge is correct?

Accepted Answer

Like charges repel and unlike charges attract.

Question 13

Which atomic model first incorporated quantum mechanics to describe the probability of finding an electron in a certain region?

Accepted Answer

The 1926 model (Schrödinger/Quantum model)

Question 14

Which of the following best explains why the mass of electrons is ignored when calculating the mass of atoms and compounds?

Accepted Answer

Electrons have a mass that is only $$\frac{1}{1836}$$ that of a proton.

Question 15

Which of the following is a correct statement about the structure of an atom?

Accepted Answer

The nucleus contains protons and neutrons, while electrons occupy the surrounding space.

Question 16

Which of the following best describes the role of atomic orbitals in chemistry?

Accepted Answer

Atomic orbitals describe the regions where electrons are likely to be found.

Question 17

Which of the following is the best explanation for why atoms of different elements have different chemical properties?

Accepted Answer

Atoms of different elements have different numbers of protons.

Question 18

Which of the following is a real-world application of understanding atomic orbitals?

Accepted Answer

Predicting the shapes and reactivity of molecules in drug design.

Atoms: Structure, Models, and Atomic Orbitals – GOB Chemistry Study Notes

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