Atomic Structure Flashcards
Who first came up with the concept of the atomic structure?
John Dalton. He created “Dalton’s Atomic Theory”
What is the first postulate of Dalton’s atoic theory?
Matter is made up of small particles called atoms. Atoms are the building blocks of an element. Element is the simplest form of substance.
What is the second postulate of Dalton’s atomic theory?
Atoms of the same element are identical, and are different from those of other elements.
What is the third postulate of Dalton’s atomic theory?
Compounds are formed when atoms of different elements combine in certain whole number ratios. Matter can be divided into pure substances and mixtures.
What is the fourth postulate of Dalton’s atomic structure?
Atoms rearrange only during a chemical reaction to form new compounds.
What did Joseph John Thompson do?
He proposed the idea of the plum pudding model. He observed in an experiment that the cathode rays could be affected by both electric and negative fields.
What is the plum pudding model?
This model showed atoms as a large positively charged area with small negatively charged particles spread throughout. This model got disproved because it did not involve a nucleus/neutrons. It was also unable to explain how the electrons were being held in place.
What did Ernest Rutherford do?
He disproved the plum pudding model by conducting the gold foil experiment. He directed a beam of positively charged alpha particles towards a piece of gold foil and he found that many of the particles passed through, thus implying that the atom is mostly empty space. This experiment also implied that an atom consists of a dense center area called the nucleus which contains protons and neutrons.
What is the nuclear model?
This model showed the atom consisting of a nucleus. It shows the electrons orbiting this nucleus. However, it was flawed in that it did not discuss the movements of electrons, only the protons and neutrons. It failed to explain the stability of the electrons in its circular path around the nucleus.
What did Niels Bohr do?
He proposed the planetary model through observations.
What is the planetary model?
This model shows the electrons encircling the nucleus in specific allowable paths called orbits. These orbits were also known as energy levels, and the electrons would only be able change orbits if it loses of gains energy. The closer the orbit is to the nucleus, the lower energy it would have, so the closer the electron is to the nucleus, the less energy it would have.
What did Erwin Schrodinger do?
He made the quantum mechanical model by incorporating the wave function.
What is the quantum mechanical model?
The quantum mechanical model treats electrons as waves, the electron cloud. The model showed the possible location of the electrons around the nucleus, with the densest part of the electron cloud being the highly probable locations of electrons.
What are protons?
These are the positively charged subatomic particles that can be found in the nucleus. It accounts for the atomic mass and it was discovered by Ernest Rutherford.
What are electrons?
These are negatively charged subatomic particles that can be found in the electron cloud. These were discovered by JJ Rhomson and they have the lightest mass/negligeble mass.
What are protons?
These are particles without any charge and can be found in the nucleus. These account for atomic mass and they were discovered by Ernest Rutherford.
