Different substances have different chemical properties, which is easy for people to understand, but why do they have different chemical properties for the same substances? Here are the reasons for the different chemical properties and atomic structures that I have compiled for you. Let’s take a look!
Reasons for different chemical properties
The number of protons in the atom is different and the number of electrons in the outermost shell is different
The molecular composition is different; < /p>
Different atomic arrangements;
Different ions
Different substances composed of the same substance have different chemical properties
Different molecular structures . Different atoms have the same chemical properties
The factor that determines the chemical properties of a substance is the number of electrons in the outermost shell of the atom
If the number of electrons in the outermost shell is the same, then the chemical properties may be the same
Isotopes, isotopes, protium, deuterium and tritium
Atomic structure
Atoms are very small. Taking carbon (C) atoms as an example, their diameter is about 140pm (picometer). But it is usually recorded in terms of radius. In the case of millimeters (mm), the diameter is 1.4X10^-7mm. It is composed of the nucleus located in the center of the atom and some tiny electrons, which move around the center of the nucleus. Just like the planets in the solar system orbit the sun. And atoms are the same as any black particle in the universe. The latest research on atomic nuclei shows that protons or neutrons in the nucleus may have a spherical vibration energy layer composed of two balancing forces, internal and external. Using this principle, various relatively stable atomic nuclei can be constructed using energy stack layers of different sizes.
① Mass number (A) = number of protons (Z) + number of neutrons (N) ② Number of protons = number of nuclear charges = number of electrons outside the nucleus = atomic number Note: neutrons determine the type of atom (isotope ), the mass number determines the approximate relative atomic mass of the atom, the number of protons (nuclear charge) determines the type of element; the number of electrons in the outermost layer of the atom determines whether the entire atom is electrically conductive, and also determines the chemical properties of the main group elements.
Atomic model
Introduction to what else is there in an atom besides electrons, how do electrons stay in an atom, what is positively charged in an atom, and how is the positive charge distributed? , how negatively charged electrons and positively charged things interact, and a lot of new questions are before physicists. Based on scientific practice and experimental observations at that time, physicists used their rich imagination to propose various atomic models. The structural model proposed by French physicist Jean Baptiste Perrin (1870-1942) in 1901 believed that the center of the atom is composed of positively charged particles, and the periphery is composed of some orbiting electrons. The period of electron rotation corresponds to the period of the atom. The emitted spectral line frequency, the outermost electron is ejected to emit cathode rays.
Neutral atom model
In 1902, German physicist Philipp Edward Anton Lenard (1862-1947) proposed the neutral particle kinetic atom model. Leonard's early observations showed that cathode rays could pass through the aluminum windows in the vacuum tube and reach the outside of the tube. Based on this observation, he used absorption experiments to prove in 1903 that high-speed cathode rays can pass through thousands of atoms. According to the prevailing semi-materialist views at the time, most of the volume of atoms is empty space, and rigid matter is only about 10-9 (that is, one hundred thousandth) of its total volume. Leonard imagined that "rigid matter" is a composite of several positive and negative charges scattered in the inner space of atoms.
Solid charged ball
The famous British physicist and inventor Lord Kelvin (1824～1907) was originally named W. Thomson (William Thomson). Due to the installation of the first For his contribution to the Atlantic submarine cable, the British government knighted him in 1866 and was promoted to Lord Kelvin in 1892, and he began to use the name Kelvin.
Kelvin's research range is wide-ranging, and he has made contributions in thermal, electromagnetic, fluid mechanics, optics, geophysics, mathematics, engineering applications, etc. He published more than 600 papers in his lifetime and obtained 70 invention patents. He enjoyed a high reputation in the scientific community at that time. Kelvin proposed the solid charged ball atomic model in 1902, which regarded atoms as uniformly positively charged spheres with negatively charged electrons buried in them. Under normal conditions, they are in electrostatic equilibrium. This model was later developed by J.J. Thomson and was later known as the Thomson atomic model.
Jujube cake model
Raisin cake model (Jujube cake model) Thomson (Joseph John Thomson, 1856-1940) continued to conduct more systematic research and tried to depict the atomic structure. Thomson believed that atoms contain a uniform positive sphere with a number of negative electrons running within this sphere. He followed Alfred Mayer's research on the equilibrium of floating magnets and proved that if the number of electrons does not exceed a certain limit, a ring formed by these running electrons will be stable. If the number of electrons exceeds this limit, it will form two rings, and so on to multiple rings. In this way, the increase in electrons results in periodic structural similarities, and the repeated recurrence of physical and chemical properties in Mendeleev's periodic table may also be explained. In this model proposed by Thomson, the distribution of electrons in a sphere is a bit like raisins dotted in a piece of cake. Many people call Thomson's atomic model the "raisin cake model". It can not only explain why atoms are electrically neutral and how electrons are distributed in atoms, but also explain the phenomenon of cathode rays and the phenomenon that metals can emit electrons under ultraviolet irradiation. Moreover, based on this model, the size of the atom can also be estimated to be about 10^-8 centimeters, which is a great thing. Because the Thomson model can explain many experimental facts at that time, it is easily accepted by many physicists.
Saturn model
Japanese physicist Nagaoka Hantaro (1865-1950) gave an oral presentation at the Tokyo Mathematical Physics Society on December 5, 1903, and presented it separately in 1904 The paper "Electron Movements in Atoms Explaining Linear and Band Spectroscopy and Radioactive Phenomena" was published in Japanese, British and German magazines. He criticized Thomson's model, believing that positive and negative charges could not penetrate each other, and proposed a structure he called the "Saturn model", that is, an atomic model with an electron ring rotating around a positively charged core. A massive positively charged ball has a circle of equally spaced electrons on the periphery that move in a circle at the same angular velocity. The radial vibration of electrons emits a line spectrum, and the vibration perpendicular to the ring surface emits a band spectrum. The electrons flying out of the ring are ? rays, and the positively charged particles flying out of the central sphere are ? rays.
This Saturn-like model was very influential in his later establishment of the nuclear model of atoms. In 1905, he analyzed the experimental results such as the measurement of the charge-to-mass ratio of the particles and concluded that the particles were helium ions. In 1908, Swiss scientist Leeds proposed the magnetic atom model. Their models could explain some experimental facts at that time to a certain extent, but they could not explain many new experimental results that appeared in the future, so they did not receive further development. A few years later, Thomson's "raisin cake model" was overturned by his student Rutherford.