Discovering the Atoms; Atomic Number and Atomic Mass

What marked the start of the modern era of chemistry?

• Dalton’s Atomic Theory 

• Law of Multiple Proportions

• Allotropes of Carbon

• Proust’s Law of Definite Proportions

What is the advantage of Dalton's idea that atoms combine in simple, whole-number ratios in the formation of compounds?

• It proves the existence of isotopes.

• It explains the concept of allotropes.

• It supports the Law of Conservation of Mass.

• It aligns with Proust's Law of Definite Proportions.

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NGSS.HS-PS1-7

According to Dalton, what is the ultimate, indivisible unit of matter?

• atoms

• electrons

• protons

• neutrons

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NGSS.HS-PS1-7

Who proposed the Plum Pudding Model, which suggested electrons are embedded in a positively charged "pudding" within the atom?

• Niels Bohr

• John Dalton

• J.J. Thomson

• Ernest Rutherford

Which subsequent model revealed the detailed structure and behavior of subatomic particles, addressing the limitations of Dalton's theory?

• Bohr's Atomic Model

• Rutherford's Atomic Model

• Quantum Mechanical Model

• Thomson's Atomic Model

What is the advantage of the Nuclear Model proposed by Ernest Rutherford?

• It recognized electrons as components of atoms.

• It introduced quantized energy levels for electrons.

• It successfully explained the spectral lines of hydrogen.

• The positive charge was localized in the nucleus of an atom.

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NGSS.HS-PS1-8

Which model successfully explained the spectral lines of hydrogen and introduced the concept of quantized energy levels for electrons?

• Nuclear Model

• Solid Sphere Model

• Planetary Model

• Quantum Mechanical Model

What disadvantage is associated with the Planetary Model proposed by Niels Bohr?

• It did not propose stable electron orbits.

• It did not explain later experimental observations.

• Electrons move around the nucleus in fixed orbits.

• Moving electrons emit energy and collapse into the nucleus.

Who proposed the Quantum Mechanical Model based on the principles of quantum mechanics, describing electrons as existing within regions of high probability called orbitals?

• Niels Bohr

• Erwin Schrodinger

• J.J. Thomson

• John Dalton

What advantage does the Quantum Mechanical Model have over earlier models regarding the movement of electrons?

• Electrons move around the nucleus in fixed orbits.

• Electrons emit energy and collapse into the nucleus.

• Electrons exist within regions of high probability called orbitals.

• Electrons are embedded in a positively charged "pudding" within the atom.