《大学化学》课程PPT教学课件（英文版讲稿）Chapter 05 Atomic Models

Chapter 5 Atomic Models Different metal containing compounds emit colored ligl when fireworks burn. This colored light is a combination of a series of colors called a spectral pattern (iE Each element emits its own characteristic spectral pattern, which can be used to identify the element This allowed the scientists in 1900s to develop models of the atoms internal structure

Chapter 5 Atomic Models Different metal containing compounds emit colored light when fireworks burn. This colored light is a combination of a series of colors called a spectral pattern. (谱带) Each element emits its own characteristic spectral pattern, which can be used to identify the element. This allowed the scientists in 1900s to develop models of the atom’s internal structure

5. 1 Models help us visualize the invisible world ofatoms Atom is very small in ing-Pong balls in the Earth

5.1 Models help us visualize the invisible world of atoms Atom is very small

We can not see them in the usual sense. This is because light travels in waves and atoms are smaller than the wavelengths of visible light, which is the light that allows the human eye to see things. So we can not see atoms through the media of light, even with a microscope An atom- A bacterum 106m (b) m

We can not see them in the usual sense. This is because light travels in waves and atoms are smaller than the wavelengths of visible light, which is the light that allows the human eye to see things. So we can not see atoms through the media of light, even with a microscope

We can see atoms indirectly through scanning tunneling microscope(STM), which was invented in 1980s. Figl: Scanning tunneling microscope fig3: an StM image of mono- Fig 2: an image of gallium laver of perylene derivative on and arsenic atoms graphite substrate, where the obtained with an stm epitaxial relationship is observed between the organic molecule and the substrate graphite

We can see atoms indirectly through scanning tunneling microscope (STM), which was invented in 1980s. fig3 : an STM image of mono￾layer of perylene derivative on graphite substrate, where the epitaxial relationship is observed between the organic molecule and the substrate graphite Fig1:Scanning tunneling microscope Fig2:an image of gallium and arsenic atoms obtained with an STM

5.2 Light is aform ofenergy requency(Hz) Gamma Ultra- Infrared Microwave Radio waves violet □留 X Sun lamps Heat Microway UHF TV FM radio VHE TV 400mm

5.2 Light is a form of energy

5.3 Atoms can be identified by the light they emit When we view the light from glowing atoms, we see that the light consists of a number of discrete frequencies rather than a continuous spectrum This is called elements atomic spectrum(原子 光谱).In1800 s researchers noted the orderliness of elements atomic spectrum, especially hydrogen, but could not give the explanation

5.3 Atoms can be identified by the light they emit When we view the light from glowing atoms, we see that the light consists of a number of discrete frequencies rather than a continuous spectrum. This is called element’s atomic spectrum (原子 光谱). In 1800s researchers noted the orderliness of element’s atomic spectrum, especially hydrogen, but could not give the explanation

氢原子光谱 抽掉氮电管中的案:充入水量氮烹g 通高压电流

氢原子光谱

5.4 Niels Bohr used the quantum hypothesis to explain atomic spectra Max Planck's quantum hypothesis(量子假设): a beam of light energy is not the continuous stream of energy, but consists of small, discrete packets of energy. Each packet was called a quantum. In 1905. Einstein recognized that these quanta of light behave like particles. Each quantum was called a photon f). light behaves as both a wave ana a particle Totally reflecting mirror Flash lamp aser beam Partially reflecting mirror

5.4 Niels Bohr used the quantum hypothesis to explain atomic spectra Max Planck’s quantum hypothesis (量子假设): a beam of light energy is not the continuous stream of energy, but consists of small, discrete packets of energy. Each packet was called a quantum. In 1905, Einstein recognized that these quanta of light behave like particles. Each quantum was called a photon (光子). Light behaves as both a wave and a particle

Electron loses Bohr 's explanation potential energy and moves closer Electron gains to nucleus. A potential photon of energy and Electron light is moves farther High potential emitted from nucleus energy A photon of light absorbed Low potential energy Nucleu

Bohr’s explanation Electron loses potential energy and moves closer to nucleus. A photon of light is emitted Electron gains potential energy and moves farther from nucleus. A photon of light is absorbed

Bohr's planetary model ofatom There are only a limited number of permitted Photon energy levels in an atom and an electron can only stay in these energy levels Each energy level has a n principal number n(主量子数) The energy level with n=1 has the lowest energy 3

Bohr’s planetary model of atom There are only a limited number of permitted energy levels in an atom, and an electron can only stay in these energy levels. Each energy level has a principal quantum number n (主 量子数). The energy level with n=1 has the lowest energy