AP Chemistry Chapter 2 Quiz (Part 1)

Electrons are negatively charged particles that orbit around the nucleus of an atom. They are one of the fundamental particles that make up atoms, along with protons and neutrons. Electrons have a much smaller mass compared to protons and neutrons, and they carry a negative charge equal in magnitude to the positive charge of a proton. Electrons play a crucial role in chemical reactions and the flow of electric current.

Isotopes are atoms that have the same number of protons but different numbers of neutrons. This means that they have the same atomic number but different atomic masses. Isotopes of an element have similar chemical properties but may have different physical properties, such as different radioactive decay rates.

Atomic is not a type of radioactive emission. The other options - beta, gamma, and alpha - are all types of radioactive emissions. Beta radiation consists of high-energy electrons or positrons, gamma radiation is high-energy electromagnetic radiation, and alpha radiation consists of helium nuclei. Atomic, on the other hand, refers to the structure and behavior of atoms and is not a form of radioactive emission.

Sodium is an element with an atomic number of 11, which means it has 11 protons in its nucleus. Protons are positively charged particles found in the nucleus of an atom. Therefore, the correct answer is 11.

The mass number of an atom is the sum of its protons and neutrons. Fluorine has 9 protons, which is its atomic number, and the given correct answer is 19. Therefore, the mass number of Fluorine is 19.

The plum pudding model, proposed by J.J. Thomson in the early 20th century, describes an atom as a diffuse cloud of positive charge with the negative electrons embedded randomly within it. This model suggests that the atom is made up of a positively charged "pudding" with the negatively charged electrons scattered throughout, similar to plums in a pudding. The model was later disproven by the experiments of Ernest Rutherford, leading to the development of the nuclear model of the atom.

The law of multiple proportions states that when two elements form a series of compounds, the ratios of masses of the second element that combine with 1 gram of the first element can always be reduced to small whole numbers. This means that the masses of the second element that combine with a fixed mass of the first element are always in whole number ratios. This law supports the idea that elements combine in fixed ratios to form compounds, providing evidence for the existence of atoms and the atomic theory.

The principle of the constant composition of compounds refers to the fact that a compound is always composed of the same elements in the same proportion by mass. This principle is known as the law of definite proportions. According to this law, the ratio of the masses of the elements in a compound is always constant, regardless of the amount of the compound. This law was first proposed by Joseph Proust in the late 18th century and is one of the fundamental principles of chemistry.

Democritus is credited with first using the term "atom" to describe small, invisible particles. He was an ancient Greek philosopher who proposed that all matter is made up of indivisible particles called atoms. Democritus believed that atoms are constantly moving and can combine to form different substances. His atomic theory laid the foundation for modern understanding of the composition and behavior of matter.

Dalton's Atomic Theory includes the idea that the mass of atoms is neither created nor destroyed. This concept is known as the Law of Conservation of Mass, which states that in a chemical reaction, the total mass of the reactants is equal to the total mass of the products. This law supports the idea that atoms are indivisible and that they cannot be created or destroyed in a chemical reaction, only rearranged.

Lavoisier is the correct answer because he conducted experiments and formulated the Law of Conservation of Mass, which states that mass is neither created nor destroyed in a chemical reaction. Lavoisier's experiments involved measuring the mass of reactants and products before and after a reaction, and he consistently found that the total mass remained constant. This discovery revolutionized the field of chemistry and laid the foundation for the concept of the conservation of mass.