An atom consist of electron, protons and neutrons. Protons and neutrons are present with in nucleus while the electrons are present out side the nucleus.
All these three subatomic particles construct an atom. A neutral atom have equal number of proton and electron. In other words we can say that negative and positive charges are equal in magnitude and cancel the each other. For example if neutral atom has 6 protons than it must have 6 electrons. The sum of neutrons and protons is the mass number of an atom while the number of protons are number of electrons is the atomic number of an atom.
Gold = Au = atomic number 79 = So it has 79 electrons
Iron = Fe = atomic number 26 = So it has 26 electrons
Copper= Cu =atomic number 29 = So it has 29 electrons
Uranium =U= atomic number 92 = So it has 92 electrons
Answer: The bigger the atom the lesser the ability of the atom to hold on to its valence electrons. Atomic radius can be looked at as the distance between the nucleus and the outermost energy level.
Answer: The discovery of three buried lakes. Scientists think that a long time ago there were lakes and rivers, etc on Mars. Now of course, you can't see any visible water sources on the surface.
