C1 Atomic structure Flashcards
what is an atom
smallest part of an element that can exist
what is Dalton’s model of the atom
atoms as solid spheres that could not 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
some alpha particles were deflected by the gold foil this showed that an atom’s mass and positive charge must be concentrated in one small space (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 levels (shells)
what did James Chadwick discover
uncharged particle called the neutron
where are protons and neutrons
in the nucleus
what is the relative mass of each sub-atomic particle
- Proton: 1
- neutron: 1
- electron: 0 (very small)
what is the relative charge of each sub-atomic particle
- Proton: +1
- neutron: 0
- electron: -1
How can you find out the number of protons in an atom
the atomic number on the periodic table
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
up to 2 in the first shell and up to 8 in the second and third shells
what is an element
substance made of one type of atom
