Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions:
Atomic were once thought to be fundamental pieces of matter, but they are in turn made of smaller subatomic particles There are three major subatomic particles neutrons, protons, and electronic. Protons and neutrons can be broken into even smaller units, but these smaller units not occur naturally in nature and are thought to only be produced in manmade particle accelerators and perhaps in extreme stellar events like supernovas. The structure of an atom can best be described as a small solar system, with the neutrons at the center and the electrons circling them in various orbits, just as the planets circle the sun. In reality, the structure of an atom is far more complex, because the laws of physics are fundamentally different at the atomic level than at the level of the observable word. The true nature of atomic structure can only be expressed accurately through complex mathematical formulas. This explanation, however, is of little use to most average people.
Protons and neutrons have nearly equal mass and size, but protons carry a positive electrical charge, while neutrons carry no charge at all. Protons and neutrons are bound together by the strong nuclear force, one of the four basic forces in the universe. Protons and neutrons give atoms some of their most basic properties. Elements are defined by two numbers: their atomic number, which is equal to the number of protons they have, and their atomic weight, which is equal to total number of their neutrons and protons. In most lighter atoms, the number of neutrons and protons is equal, and the element is stable. In heavier atoms, however, there are more neutrons than protons, and the element is unstable, eventually losing neutrons through radioactive decay until a neutral state is reached.
Electrons are negatively charged particles. They are bound to their atoms through electromagnetic attraction. Opposite electrical charges attract one another, so the positive charge of the proton helps to keep the negatively charged electron in orbit around the nucleus of the atom. Electrons are different from neutrons in that they cannot be broken down into smaller particles. They are also far smaller and lighter than neutrons and protons. An electron is about one thousandth of the diameter of a proton and an even smaller fraction of its mass. Electrons circle the protons and neutrons at the center of the atom in orbits. These orbits are often called electron shells. The closer the orbit is to the center of the atom, the lower its energy is. There are seven electron shells, and each higher level can hold more electrons than the previous shell. Electrons naturally seek to occupy the lowest shell possible. So, if there is space in a lower shell, an electron will drop down to occupy that space. At temperatures higher than a few hundred degrees, electrons will gain energy and move to a higher shell, but only momentarily. When the electrons drop back down to their natural shell, they emit light. This is why fires and other very hot objects seem to glow.
Electrons are also primarily responsible for many of the chemical properties of atoms. Since electrons seek to occupy the lowest electron shell possible, they will move from one atom to another if there is a space available in a lower electron shell. For example, if there is an atom with an open space in its third shell, and it comes into contact with an atom with electrons in its fourth shell, the first atom will take one of these electrons to complete its third shell. When this happens, the two atoms will be chemically bonded to form a molecule. Furthermore, atoms sometimes lose electrons in collisions with other atoms. When this happens, the radio of protons and electrons in the atom changes, and therefore, the overall electrical charge of the atom changes as well. These atoms
Suy nghĩ và trả lời câu hỏi trước khi xem đáp án
Lời giải:
Báo saiKiến thức: Đọc hiểu Giải thích:
Trong đoạn 1, tại sao tác giả lại so sánh cấu trúc của một nguyên tử với hệ Mặt Trời?
Để đưa ra một lời giải thích về cấu trúc nguyên tử một cách dễ hiểu.
Để chỉ ra ảnh hưởng của cấu trúc nguyên tử đến thế giới ở cấp độ quan sát được.
Để chỉ ra rằng các công thức toán học phức tạp được sử dụng để giải thích cấu trúc nguyên tử là không chính xác.
Để tương phản kích thước của các nguyên tử với kích thước của các vật thể ở mức có thể quan sát được.
Thông tin: The structure of an atom can best be described as a small solar system, with the neutrons at the center and the electrons circling them in various orbits, just as the planets circle the sun.
Tạm dịch: Cấu trúc của một nguyên tử có thể được mô tả chính xác nhất giống như một hệ mặt trời nhỏ, với các nơtron ở trung tâm và các electron quay quanh chúng theo các quỹ đạo khác nhau, giống như các hành tinh quay quanh Mặt Trời.