C1.2 - Atomic Structure Flashcards
What does the number of protons, neutrons, electrons and mass number tell us?
Number of protons = atomic number
Number of neutrons = mass number - atomic number
Number of electrons = the number of protons ( ONLY IN ATOMS )
Mass number - Number of protons + number of neutrons
What is the 12 and the 6?
12 = mass number ( always the largest )
6 = Atomic number
What are isotopes ?
Isotopes of an element are the atoms with the same number of protons and electrons ( same atomic number ) but a different number of neutrons ( different mass number )
What are ions?
They are charged particles
What happens when an atom loses or gains electrons?
- Atoms that lose electrons form positive ions ( cations ) e.g. Na+
- Atoms that gain electrons from negative ions ( anions ) e.g. Cl-
When are ions formed ?
When an atom or group of atoms gains or loses one or more electron
What did the initial atom model look like? draw it
What did the plum-pudding model look like? Draw it
What did Earnest Rutherford’s model look like? Draw it
What did Niels Bohr’s model look like? Draw it
Describe the plum-pudding model?
The model described the atom as a cloud of positive charge which contained smaller negatively charged particles called electrons
Describe Earnest Rutherford’s model?
A small positively charged nucleus is found at the centre of the atom, it is surrounded by a cloud of negative electrons. Most of the atom is empty space.
What is the timeline for developing the atomic model timeline?
John Dalton ( 1803 ) —> J.J.Thomson ( 1897 ) —> Earnest Rutherford ( 1909) —> Niels Bohr ( 1913 )
What did John Dalton suggest?
- That all matter Is made from solid atoms
- All atoms of an element are identical
- Different elements contain different types of atoms
What did J.J.Thomson discover and propose ?
- Discovered the electron by experimenting with cathode rays
- Proposed the ‘plum-pudding’ model of the atom to show:
. Atoms contain electrons
. Atoms have no overall charge
