The Atom Flashcards
What is an atom?
smallest part of an element that can exist
What was Dalton’s model of the atom?
solid spheres which could not be divided into smaller parts
What is the plum pudding model of the atom and who created it?
sphere of positive charge with negative electrons embedded into it - J.J. Thompson
What did scientists discover in the alpha particle 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 (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?
an 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: very small (1/1836)
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 and negative charge (protons and electrons)
How many electrons would you place in the 1st, 2nd and 3rd shells?
1st: 2, 2nd: 8, 3rd: 8
What is an element?
a substance made of one type of atom
