the central section of the atom
made up of sub-atomic particles called protons and neutrons
sub-atomic particles that revolve around the nucleus in paths called orbits
this movement of electrons creates an electron cloud
Protons have a positive charge (Charge = +1)
Electrons have a negative charge (Charge = -1)
Neutrons are neutral (No charge)
Usually atoms are electrically neutral which means that the number of protons in the atom is equal to the number of neutrons.Protons and neutrons have the same mass, but electrons are 2000 times smaller than the mass of proton. (>>>>>>)
Caption: : Helium: Atomic number = 2, Mass number = 4
number of fluorine is 9 and its mass number is 19. (rounded from 18.998, see left)
How many (a) protons,
(b) electrons and (c) neutrons does a neutral fluorine atom have?
(a) 9 protons(b) 9 electrons (same number as the number of protons)(c) 10 neutrons (19
to think that all atoms of a particular element were identical. We have discovered that some elements have two or three different types of atom.They will all
have the same number of protons but they could have a different number of
e.g. some atoms
of carbon have 6 neutrons, while other atoms of carbon have 7 neutrons, and others have 8 neutrons.
We say these
atoms are isotopes of each other.
are atoms that have the same atomic number but a different mass number