What does the atomic number of an element represent?
The atomic number is the number of protons found in the nucleus of an atom.
Also, if in it's pure elemental form, the number of electrons.
Each box on the periodic table has two numbers in it. The number on top is the atomic number. The number on bottom is the relative atomic mass. The atomic number is the number of protons each atom of the element contains. The relative atomic mass is the mass in grams of one mole of the element with the relative percentages of the isotopes taken into consideration.
If there is a difference between a substance's atomic number and its atomic mass and which measure must be the larger number?
If there is a difference between a substance atomic number and its atomic mass which measure must be the larger number?
If you are referring to the whole numbers, then they represent the atomic number (or the number of protons or the number of electrons) of the element. If you are referring to the numbers with the decimals, then they represent the atomic mass of the element. In addition certain version of periodic table also lists the group number (from 1 to 18), the period number (from 1 to 7), the electronic configuration, etc.
There is no such element. Atomic numbers represent how many protons are in the nucleus of an atom. Lithium's atomic number is three; it has three protons. An atom with 35.543 protons can't exist because there can't be a fraction of a proton - how can you have 35 and .543 protons? I think perhaps you confused atomic number with atomic mass. Chlorine's atomic mass is 35.543 grams.