Atomic structure -1 Flashcards
(26 cards)
What did Robert Boyle do and when did he do it
He proposed that there were some substances that could not be made simpler. These are the chemical elements we know. He proposed this in 1661.
What did John dalton do and when
In 1803 he suggested that elements were composed of invisible atoms. All the atoms of a particular element had the same mass and atoms of different elements had different masses and atoms could not be broken down.
What did Henri becquerel do and when
In 1896 he discovered radioactivity which showed that particles could come from inside the atom which meant that the atom was not indivisible
What and when did JJ Thomson do
In 1897 he discovered the electron which was the first sub-atomic particle which was discovered. He showed that electrons were negatively charged and electrons from all elements were the same.
Also he suggested that electrons were located within the atom in circular rays, this is because electrons had a negative charge there had to be a source of positive charge inside the atom and because electrons are much lighter than whole atoms there had to be something to account for the rest of the mass of the atom.
What did Ernest Rutherford do and when
In 1911 him and his team found that most of the mass and all the positive charge of the atom was in tiny central nucleus.
What instrument can be used to take a photograph of an atom
Atoms can only be seen indirectly. A scanning tunnelling electron microscope
What are protons and neutrons some times called
Nucleons
What is the relative mass of a proton
1
What is the relative mass of a neutron
1
What is the relative mass of an electron
1840
What is the relative charge of a proton
+1
What is the relative charge of a neutron
0
What is the relative charge of an electron
-1
How are protons and neutrons held together
Strong nuclear force
What holds electrons and protons together and where and how long does it happen
Electrostatic forces and it happens within the nucleus over very short distances
What is stronger electrostatic force or strong nuclear force and what does this mean
Strong nuclear force which means that it overcomes repulsion in the protons in the nucleus.
Why do we assume that there are the same number of protons and electrons in an atom
Because they have opposite charges of the same size and the atom is neutral
Who were the main alchemists that developed the ideas of the atom
Robert Boyle John dalton Henri becquerel JJ. Thomson Ernest Rutherford
The number of electrons is equal to the number of protons so what does this mean for the whole atom
The atom is electrically neutral
What determines the chemical properties of an element and what sort of element it is
The number of electrons in the outer shell
What does the atomic number define
The chemical identity of an element
Calculating mass number
Protons + neutrons
What is responsible for almost all the mass of an atom
Protons and neutrons because electrons weigh virtually nothing
What is an isotope
Same proton number different number of neutrons
React chemically in the same way
