Combined Higher Flashcards
What is an atom?
Smallest part of an element that can exist
What is Dalton’s model of the atom?
Atoms are solid spheres that cannot be divided into smaller parts
What is the plum pudding model of the atom?
Sphere of positive charge with negative electrons embedded in it
What did scientists discover in the alpha scattering experiment?
An atom had something positive and small with mass in its centre - the nucleus
Describe the nuclear model of the atom?
Dense nucleus with electrons orbiting it.
What did Niels Bohr discover?
Electrons orbit in fixed energy shells
What did james Chadwick discover
The neutron
Where are protons and neutrons found?
In the nucleus
What is the relative mass of each sub atomic particle
Electron 0
Proton 1
Neutron 1
What is the relative charge of each sub atomic particle?
Electron -1
Proton +1
Neutron 0
How can you find out the number of protons in an atom?
Atomic number
How can you calculate the number of neutrons in an atom?
Mass number - atomic number
Why do atoms have no overall charge?
Equal numbers of positive protons and negative electrons
How many electrons would you place in the first, second and third shells?
2,8,8
What is an element?
Substance made up of one type of atom
