Chemistry 121 Chapter 2 Part 2

Explanation
The mass number represents the total number of protons and neutrons in an atom's nucleus. In the given question, the top number next to each element is referring to the mass number because it provides information about the total number of particles in the nucleus. The atomic number, on the other hand, represents the number of protons in an atom's nucleus.

Explanation
The bottom number next to each element is the atomic number. The atomic number represents the number of protons in the nucleus of an atom, which determines the element's identity. It is a unique characteristic of each element and is used to organize the elements in the periodic table. The mass number, on the other hand, represents the total number of protons and neutrons in an atom, which can vary for different isotopes of the same element.

Explanation
The atomic number of an element represents the number of protons in its nucleus. It is a unique identifier for each element and determines its position on the periodic table. The mass number, on the other hand, represents the total number of protons and neutrons in an atom. Therefore, the correct answer is "atomic number."

Explanation
The mass number of an atom is the sum of the number of protons and neutrons in its nucleus. It provides information about the total number of nucleons in an atom, which includes both protons and neutrons. The atomic number, on the other hand, only tells us the number of protons in an atom. Therefore, the mass number is the correct answer as it specifically refers to the number of protons and neutrons in an atom.

Explanation
The number of protons in an atom is equal to its atomic number. In the given picture, the number 92 is written on the bottom left, which represents the atomic number of Uranium. Therefore, the number of protons in Uranium is 92.

Explanation
The number of neutrons can be calculated by subtracting the atomic number (92) from the atomic mass (238). In this case, 238 - 92 = 146. Therefore, the number of neutrons is 146.

Explanation
Isotopes are elements that have the same atomic number but different mass numbers. This means that they have the same number of protons in their nucleus but a different number of neutrons. Due to the difference in the number of neutrons, isotopes may have slightly different physical and chemical properties, but they still belong to the same element. Therefore, the correct answer is "isotopes."

Explanation
The isotope is A because it has the same atomic number (92) as B, indicating that they are both uranium atoms. However, A has a different mass number (235) compared to B (238), indicating that they have different numbers of neutrons and therefore belong to different isotopes of uranium.

Explanation
Francis William Aston is the correct answer because he invented the mass spectrometer, which is a crucial tool in elemental analysis and analytical chemistry. The mass spectrometer allows scientists to determine the mass and composition of molecules, ions, and isotopes in a sample. This information is essential for understanding the structure and behavior of substances in various fields of study, such as chemistry, physics, and biology. Antoine Lavoisier and Isaac Newton made significant contributions to science, but they did not invent the mass spectrometer.

Explanation
Avogadro's number is a fundamental constant in chemistry that represents the number of atoms, molecules, or particles in one mole of a substance. It is defined as 6.022 x 10 to the 23rd power, which means that one mole of any substance contains 6.022 x 10 to the 23rd power particles. This number is derived from experiments and is used to convert between the mass of a substance and the number of particles it contains.

Explanation
An ion is an atom or molecule that has a distinct charge associated with it. It can be positively charged (cation) or negatively charged (anion) depending on whether it has lost or gained electrons. The atomic number, on the other hand, refers to the number of protons in the nucleus of an atom. While protons are positively charged particles found in the nucleus of an atom, they do not necessarily have a distinct charge associated with them. Therefore, the correct answer is Ion, Atomic Number.

Explanation
A positive ionic molecule is called a cation. Cations are formed when an atom loses one or more electrons, resulting in a positive charge. They are attracted to the negatively charged anions and are an essential part of ionic compounds. Cations play a crucial role in various chemical reactions and are commonly found in salts and other compounds.

Explanation
An anion is a negatively charged ion that is formed when an atom gains one or more electrons. In contrast, a cation is a positively charged ion that is formed when an atom loses one or more electrons. Since the question asks for a negative ionic molecule, the correct answer is an anion. An example of a negative ionic molecule is chloride ion (Cl-) which is formed when a chlorine atom gains one electron.