Bk Ch 1 Discovery Of The Atom Quiz

Explanation
Democritis, a Greek philosopher, proposed the theory that all matter is composed of atoms. This theory suggests that atoms are the fundamental building blocks of everything in the universe. Democritis believed that these atoms are indivisible and indestructible, and that they combine in different ways to form various substances. His theory laid the foundation for modern atomic theory and has been supported by numerous scientific discoveries and advancements. Therefore, the statement is true.

Explanation
The given statement is false. JJ Thompson did not combine the idea of elements with the Greek theory proposed by Democitris. Instead, Thompson is known for his discovery of the electron and his model of the atom, known as the "plum pudding" model. The Atomic Theory, which relates to the concept of elements and atoms, was developed by John Dalton in the early 19th century.

Explanation
The Atomic Theory stated that matter is made of atoms, not molecules. Atoms are the basic building blocks of matter and cannot be broken down into smaller particles, while molecules are formed when two or more atoms chemically bond together. Therefore, the statement that matter is made of molecules is incorrect according to the Atomic Theory.

Explanation
The Atomic Theory, proposed by John Dalton, states that atoms are indivisible and cannot be divided into smaller pieces. According to this theory, atoms are the fundamental building blocks of matter and retain their identity throughout chemical reactions. This idea revolutionized the understanding of chemistry and laid the foundation for modern atomic theory. Therefore, the statement that atoms can be divided into smaller pieces is incorrect.

Explanation
The Atomic Theory, proposed by John Dalton, states that all atoms of an element are exactly alike. This means that atoms of the same element have the same number of protons, neutrons, and electrons, giving them identical chemical properties. This principle is fundamental to our understanding of the periodic table and the behavior of elements in chemical reactions. It also helps explain why elements can form compounds and why chemical reactions occur. Therefore, the statement that all atoms of an element are exactly alike is true according to the Atomic Theory.

Explanation
The Atomic Theory, proposed by John Dalton in the early 19th century, states that different elements are composed of different atoms. This means that each element has its own unique type of atom with specific properties. This theory was developed based on experimental evidence and has been widely accepted in the field of chemistry. Therefore, the statement that different elements are made of different atoms is true according to the Atomic Theory.

Explanation
The statement is true because William Crookes indeed used a cathode-ray tube that produced a greenish glow. Initially, he believed that the phenomenon was supernatural, but later he became convinced that it was caused by charged particles. This suggests that Crookes' experiments with the cathode-ray tube led him to understand the nature of the glow and its connection to charged particles.

Explanation
JJ Thompson did revise Crookes experiment and used a magnet to attract the greenish glow. However, his discovery was not about neutral charges in an atom. Instead, Thompson discovered the existence of negatively charged particles, which he called electrons. This discovery led to the development of the plum pudding model of the atom, in which electrons were embedded in a positively charged sphere. Therefore, the correct answer is False.

Explanation
JJ Thompson revised Dalton's model of the atom by proposing the "plum pudding" model. In this model, Thompson suggested that atoms were made up of a positively charged sphere with negatively charged particles, called electrons, spread throughout. This was a significant revision to Dalton's model, which proposed that atoms were indivisible and indestructible. Thompson's model provided evidence for the existence of subatomic particles and laid the foundation for further understanding of atomic structure. Therefore, the statement "JJ Thompson revised Dalton's model of the atom. Thompson's model looked like a sphere that was positively charged with negatively charged particles spread throughout" is true.

Explanation
Earnest Rutherford tested Thompson's model and found that it was inaccurate. Rutherford conducted the gold foil experiment, where he bombarded a thin gold foil with alpha particles. According to Thompson's model, the positive charge in an atom was spread out evenly, so the alpha particles should pass through the foil with minimal deflection. However, Rutherford observed that some alpha particles were deflected at large angles and even bounced back. This led him to conclude that Thompson's model was inaccurate and proposed his own model, known as the nuclear model, which suggested that the positive charge in an atom is concentrated in a small, dense nucleus.

Explanation
Rutherford's experiment involved firing alpha particles at a thin gold foil. He observed that most of the alpha particles passed straight through the foil, suggesting that there was a large amount of empty space in the atom. However, a small number of alpha particles were deflected at large angles, indicating the presence of a small, dense nucleus in the atom. This experiment confirmed the existence of a nucleus and the fact that most of the atom is indeed empty space.

Explanation
The statement is false because after Rutherford's experiment, scientists actually discovered that there must be neutrons in the atom, not electrons. Rutherford's experiment showed that most of the mass of an atom is concentrated in a small, dense nucleus, and the electrons are located outside the nucleus. Therefore, the mass of an atom is not solely determined by the protons, but also by the neutrons in the nucleus.

Explanation
Thompson was not well known for trying to prove the existence of supernatural beings.

Explanation
Niels Bohr is credited with developing the current model of the atom, known as the Bohr model. This model proposed that electrons orbit the nucleus in discrete energy levels, and it successfully explained the spectral lines observed in hydrogen and other elements. Bohr's model was a significant advancement in understanding the structure of atoms and laid the foundation for further developments in quantum mechanics.

Explanation
The current model of an atom, known as the electron cloud model or the quantum mechanical model, describes the electrons in an atom as existing in a region of space surrounding the nucleus called the electron cloud. This model suggests that the exact location of an electron within the cloud is uncertain, and instead, it is more accurate to describe the probability of finding an electron in a particular region. This concept is supported by experimental evidence and is widely accepted in the field of modern physics.