Most of the volume of the atom is empty space
Image: User Yzmo Wikimedia Commons.
Protons and neutrons are NOT fundamental particles.
Protons are made of two “up” quarks and one “down” quark.
Neutrons are made of one “up” quark and two “down” quarks.
Quarks are held together by “gluons”
Images: Arpad Horvath, Wikimedia Commons.
Isotopes are atoms of the same element having different masses due to varying numbers of neutrons.
Atomic mass is the average of all the naturally isotopes of that element.
Carbon = 12.011
Atomic number (Z) of an element is the number of protons in the nucleus of each atom of that element.
Mass number is the number of protons and neutrons in the nucleus of an isotope.
Mass # = p+ + n0