Atoms Flashcards
How did scientist classify elements before the discovery of protons neutrons and electrons
scientists attempted to classify the elements by arranging them in order of their atomic weights.
What was wrong with the early periodic tables
The early periodic tables were incomplete and some elements were placed in inappropriate groups if the strict order of atomic weights was followed.
What did Mendeleev do to overcome some problems he had
Left gaps for elements that he thought would be discovered and also changed the ird3r depending on the atomic weights
How was the theory of putting elements in atomic weight order wrong
As there are isotopes
Before the discovery of electrons atoms where thought to be
Tiny spheres that were indivisible
The discovery of the electron led to the plum pudding model of the atom. What was the plum pudding model ?
The plum pudding
model suggested that the atom is a ball of positive charge with negative electrons
embedded in it.
What was learnt from the alpha particle experiment
Mass of an atom was concentrated at the centre (nucleus) and that the nucleus was charged. This
nuclear model replaced the plum pudding model.
What did Niels Bohr do to the nuclear model
suggesting that electrons orbit the nucleus at
specific distances. The theoretical calculations of Bohr agreed with experimental
observations.
Later more experiments were conducted on the nucleas what was found out
the positive charge of any nucleus could be
subdivided into a whole number of smaller particles, each particle having the same amount
of positive charge. The name proton was given to these particles.
What did James Chadwick’s experimental work show us on the existence of neutrons
provided the evidence to show the existence of
neutrons within the nucleus. This was about 20 years after the nucleus became an accepted
scientific idea.
why the new evidence from the scattering experiment led to a change in the atomic model
As it told us that there was a dense cluster f particles in the middle and that that middle was positively charged . It also tells us that there is a lot more space in the atom
Whats the two main differences between plum pudding and nuclear models
Plum pudding suggested that all the particles are spread out however nuclear proposed that there was a dense cluster of particles in the middle . Also the nuclear model suggested that an atom is a ball of postoperative charge with electrons in it . Where as nuclear suggested that the atom is neutrally charged
How does the fact that something is a metal or non metal affect the ions
Elements that react to form positive ions are metals. Elements that do not form positive ions are non-metals.
Why is an element in a certain group
Due to the fact that it has a certain amount of electrons in its outer shell
Ram for chlorine 35 75 percent and ram for chlorine 37 25 percent
RAM = 35 75 + 3725
Divided by 100
35.5
