GCSE Atomic Structure Flashcards
History of structure of the atom:
Early 1800’s;
In his theory what did dalton state
- All elements are made up of small invisible particles called atoms
- Atoms can’t be created or destroyed
- Atoms of different elements have different properties
- When atoms combine they form molecules or compounds
History of structure of the atom:
1897 ‘Plum Pudding’ model of J.J Thomson: Who discovered the electron
J.J Thomson
History of structure of the atom:
1897 ‘Plum Pudding’ model of J.J Thomson: When J.J Thomson discovered the electron what happened to dalton’s atomic theory
It was modified
History of structure of the atom:
1897 ‘Plum Pudding’ model of J.J Thomson:
What did J.J Thomson propose
He proposed the ‘plum pudding’ model which stated that the negative electrons were embedded in a positive sphere (like the raisins in a plum pudding)
History of structure of the atom:
What happened in 1911
Ernest Rutherford revised J.J Thomson’s model to the model which has electrons orbiting a positive nucleus
History of structure of the atom:
What happened in 1932
James Chadwick discovered the neutron
Comprehension questions:
Who proposed the idea that matter is composed of small indivisible particles called atoms
Democritus and Leucippus
Comprehension questions:
What ideas did Aristotle propose
That matter was composed of 4 ‘elements’, air, earth, fire and water and he used these ideas to explain matter and its behaviour
Comprehension questions:
In 1908 John Dalton published his atomic theory, what did he state
That all elements are made up of small indivisible particles called atoms
Comprehension questions:
Name the scientist who discovered the electron
J.J Thomson
Comprehension questions:
What experiment was Thomson carrying out when he discovered the electron
The way gases conduct electricity
Comprehension questions:
In Thomson’s experiment how did he show the electrons had a negative charge
He passed high voltage across the terminals of a tube containing air and found out that the rays produced travelled in straight lines from the negative terminal and at these rays were deflected when they passed through charged plates
Comprehension questions:
What did Thomson’s model of the atom look like
A plum pudding
Comprehension questions:
How was it similar to a Christmas pudding
There are rings of negative electrons embedded in a sphere of positive charge, just like the currants embedded in a Christmas pudding
Comprehension questions:
Why did Thomson suggest that the atom was neutral
Because it contained equal numbers of positive and negative charges
Comprehension questions:
What did Rutherford discover about the atom
It consisted of electrons revolving around a positively charged nucleus
Comprehension questions:
Where is virtually all of an atoms mass contained
In the nucleus
Comprehension questions:
In what way was Rutherford’s model of the atom similar to planets revolving around the sun
The electrons revolving around the positively charged nucleus were like the planets revolving around the sun
Comprehension questions:
What part of the atom did James Chadwick discover in 1932
He showed that the nucleus of an atom contained 2 different types of particles, protons and new particles called neutrons
Comprehension questions:
How does the mass of a neutron compare with the mass of a proton
It is equal
Fill in the blanks:
Atom is composed of a small, dense, ………… charged nucleus composed of……….and……….with…………charged electrons in…….orbiting the……..
Positively Neutrons Protons Negatively Shells Nucleus
Give the relative mass (atomic mass units), relative charge and position of the following particles:
Proton
Neutron
Electron
Proton:
Relative mass = 1
Relative charge = +1
Position = nucleus
Neutron:
Relative mass = 1
Relative charge = 0
Position = nucleus
Electron:
Relative mass = 1/1840
Relative charge = -1
Position = shells
Definition of atomic number
This is the number of protons in an atom
Definition of mass number
This is the total number of protons and neutrons in an atom
