PES Science Flashcards
What are some of the ideas that John Dalton had?
- John Dalton believed that atoms:
- Could not be divided
- We all alike for the same element
- Could chemically combine with other atoms
Democritus
Used Logic
- All matter is made from atoms
- No-cut (could not break further)
- Were invisible particles
- differend shapes and size.
Dalton
Believed that Atoms could not be divided, were like for elements and could chemically combine with other atoms
Used Logic
Thomson
He found the Electron
Used cathode rays—when wires are put at the edge of a glass tube and as much air is pumped into it, the cathode ray will be formed
Did 3 Experiments
- Wanted to show that the rays emitted from the gun were inseperable. He built a cathode ray tube with a metal cylinder with slits at the end. By using magnets, he recorded that there was no recording that the electric charge had been bent.
- Had to prove that the cathode rays carried a negative charge.cathode ray tube, with a fluorescent coating at one end and a near perfect vacuum. Halfway down the tube were two electric plates, producing a positive anode and a negative cathode, which he hoped would deflect the rays.The rays were deflected towards the positive plate which proved that the particles carried a negative charge.
- Found the properties of the electron.Used deduction to find particle size.
Rutherford
Atoms have a centrally located positively charged nucleus with electrons around it.
Found Proton
Rutherford had conducted experiments in which he shot relatively large, charged particles (alpha particles) at a thin gold foil. He found that most of the particles passed directly through the foil, but some came off at odd angles, as though they had been deflected. From these results, Rutherford concluded that each atom was mostly empty space, but also contained a dense region–a central mass, which his alpha particles could not pass through. He also concluded that this central mass must have a positive charge, to deflect the positively charged alpha particles.
chadwick
Discovered neutrons
By bombing beryllium with particle to produce radial and using the produced radial to bomb hydrogen and nitrogen, he produced hydrogen nuclear and nitrogen nuclear. Based on this result, he concluded that this radial was absolutely not radial. Because radial had no momentum to produce proton from atom. He believed that this was reasonable only when this radial from beryllium was a kind of neutral particle with a mass similar to the proton.
Bohr
He discovered that electrons were in different energy levels
Bohr placed energy in a long black tube where there were hydrogen atoms in it.
Saw that there was a colored light that came out.
Why Does This Happen?
1. If energy is added to the atom-electrons would automatically jump to higher energy
levels or orbits
2.But, they are still attracted to the nucleus, so they fall back to the original orbit
releasing energy
3.The amount the electron falls determines the amount of energy released
4. The energy is given off as a color
5.
6.
Because when this happens, different atoms give of different colors
This means that the atoms of a different type must have different orbits BUT do
have different energy levels
What are the 3 basic subatomic particles
3.The 3 basic subatomic particles are proton, neutron, and electron. Protons are 1 a.m.u. And they are positively charged in the nucleus-determine element. Electrons are 1/1836 a.m.u. They are negatively charged and are located in energy levels around the nucleus determine chemical reactions. Neutrons are neutrally charged in the nucleus and they are around 1 a.m.u affect stability.
What is the difference between the Bohr model and the electron orbit models
- In the Bohr model. You see the electrons as if they were in actual circular orbits. In the electron cloud model, the position and orbit of an electron are only determined with probability.
- An atom that has a varying amount of neutrons—it has to have equal amount of protons and electons because they cross each other out.
Mass Number and Atomic Number
3.MEA Mass Number- the number of Protons and Neutrons added together, Atomic Number-the number of protons
What is average atomic mass?
Average Atomic Mass- is the weighted average of all the different isotopes of an element (under letter in periodic table) –(% abundance)(mass) -(% abundance)(mass) Atomic Mass is the mass of that specific isotope
What are the energy levels?
What is the role of valence electrons
3.Valence Electrons are the electrons that determine how the atom chemically bonds. They are in the outermost level. The valence shell, is the outermost shell of electrons.
What is electron configuration?
3.Electron configuration is basically showing how many electrons are in each energy level. So, a-b-c is a configuration that shows how many electrons are in each level. The numbers cannot exceed the amount of electrons that are permitted in each energy level. An electron dot diagram shows how many valence electrons each atom has. They are in pairs on each side.
What is a rule for valence electrons?
In a Dot Diagram only do the Valence Electrons
3.The number of valence electrons in the tall columns is the family number or the number on the column. In the shorter columns, it is the number -10.
