https://padlet.com/2358821/36ct3sc4acg3znvy A Timeline about Atomic Structure en-us 2021-10-15 18:21:27 UTC 2025-10-14 22:47:05 UTC hello@padlet.com https://padlet.net/icons/png/1f47e.png 2358821 https://padlet.com/2358821/36ct3sc4acg3znvy/wish/1820243737 1- Dalton's theory additionally examined the compositions of compounds explaining that the tiny particles in a compound were compound atoms.
2- He also uncovered the fact that atoms couldn't be created or destroyed.
3- He became the first scientist to explain the behavior of atoms in terms of the measurement of weight.]]> 2021-10-15 18:35:18 UTC https://padlet.com/2358821/36ct3sc4acg3znvy/wish/1820243737 2358821 https://padlet.com/2358821/36ct3sc4acg3znvy/wish/1820245705 1- negatively-charged electrons embedded within a positively-charged soup
2- Thomson's experiments with cathode ray tubes showed that all atoms contain tiny negatively charged subatomic particles or electrons 
3- Thomson realized that the accepted model of an atom did not account for negatively or positively charged particles.]]> 2021-10-15 18:36:33 UTC https://padlet.com/2358821/36ct3sc4acg3znvy/wish/1820245705 2358821 https://padlet.com/2358821/36ct3sc4acg3znvy/wish/1820247393 1- The whole mass of the atom is concentrated in the center of atom called nucleus
2- The positively charged particles are present in the nucleus of atom
3- He was the first to discover that atoms have a small charged nucleus surrounded by largely empty space, and are circled by tiny electrons, which became known as the Rutherford model of the atom.]]> 2021-10-15 18:37:40 UTC https://padlet.com/2358821/36ct3sc4acg3znvy/wish/1820247393 2358821 https://padlet.com/2358821/36ct3sc4acg3znvy/wish/1820248279 1-  He proposed that electrons are arranged in concentric circular orbits around the nucleus
2- That the energy of an electron is quantized, meaning electrons can have one energy level or another but nothing in between.
3- Electromagnetic energy will be absorbed or emitted if an electron moves from one orbit to another.]]> 2021-10-15 18:38:15 UTC https://padlet.com/2358821/36ct3sc4acg3znvy/wish/1820248279 2358821 https://padlet.com/2358821/36ct3sc4acg3znvy/wish/1820249160 1- The quantum mechanical model of the atom uses complex shapes of orbitals 
2- These quantized values of energy are obtained from the solution of Schrodinger Wave Equation 

]]> 2021-10-15 18:38:50 UTC https://padlet.com/2358821/36ct3sc4acg3znvy/wish/1820249160 2358821 https://padlet.com/2358821/36ct3sc4acg3znvy/wish/1820251478 1- A cathode ray tube or CRT is a device that produces cathode rays in a vacuum tube and accelerates them through a magnetic and electric field to strike on a fluorescent screen to form images.
2- Johann Hittorf discovered cathode rays in 1869 in Crookes tubes
3- Crookes tubes partially vacuum tubes having two electrodes kept at a high potential difference to discharge cathode rays from the negatively charged electrode cathode.]]> 2021-10-15 18:40:25 UTC https://padlet.com/2358821/36ct3sc4acg3znvy/wish/1820251478 2358821 https://padlet.com/2358821/36ct3sc4acg3znvy/wish/1820251991 1- A piece of gold foil was hit with alpha particles, which have a positive charge. Most alpha particles went right through. This showed that the gold atoms were mostly empty space.
2- Some particles had their paths bent at large angles. A few even bounced backward. The only way this would happen was if the atom had a small, heavy region of positive charge inside it.
3- The gold-foil experiment showed that the atom consists of a small, massive, positively charged nucleus with the negatively charged electrons being at a great distance from the centre]]> 2021-10-15 18:40:47 UTC https://padlet.com/2358821/36ct3sc4acg3znvy/wish/1820251991 2358821 https://padlet.com/2358821/36ct3sc4acg3znvy/wish/1820254167 1- Bohr's model of the hydrogen atom explains the emission and absorption spectra of atomic hydrogen and hydrogen-like ions with low atomic numbers
2- It was the first model to introduce the concept of a quantum number to describe atomic states and to postulate quantization of electron orbits in the atom
3- Bohr was the first to discover that electrons travel in separate orbits around the nucleus and that the number of electrons in the outer orbit determines the properties of an element]]> 2021-10-15 18:42:16 UTC https://padlet.com/2358821/36ct3sc4acg3znvy/wish/1820254167