How is the periodic table of elements composed, what are the numbers and abbreviations?

I don't need to know details about the elements, but know which is the atomic number/mass, and the... make-up of a single box on the table of elements. I can't exactly say what I'm trying to ask.

I am asking about in a box what is what.How is the periodic table of elements composed, what are the numbers and abbreviations?
The letters refer to the atomic symbol for the element



The smaller number (always a whole number) usually on the upper left is the atomic number and is the number of protons which equals the number of electrons for stable atoms.



The larger usually non whole number (like 12.011) is the atomic mass. it is actually a weighted average atomic mass for all the known isotopes of that element. FYI. essentially all the mass is found in the nucleus of the atom (the protons + the neutrons).



The number of neutrons = the atomic mass - the atomic number



Remember this. The number of protons dictates the element. The number of electrons = the number of protons unless you have an ion. The number of neutrons can vary and the same elements with different numbers of neutrons are called isotopes.



For example Uranium (atomic symbol U) has atomic number 92. That is, it has 92 protons and 92 electrons. U235 has 143 neutrons. why? U238 has 146 neutrons. again why? (hint 238-92 = ?)



The atomic mass of U is calculated by considering that 99.3% of naturally occuring U is 238 and 0.7% is U235. (.993*238 + .007*235 = weighted average atomic mass).



The rows and columns indicate the electronic configuration and how the atom bonds.How is the periodic table of elements composed, what are the numbers and abbreviations?
Lexa. Good luck in your studies. let me know if i can be of further assistance. my background, fyi, is chemical engineering.

Report Abuse

The smaller number is the atomic number (the number of protons in the atom), the larger one is the atomic mass. If there's only one number, it's the atomic number. The letter or letters are an abreviation for the name of the element; sometimes it has to do with what we call the element in English, like H for hydrogen or Li for lithium, and sometimes it comes from another language, such as Pb for lead from the Latin word plumbum.
Ok look at Carbon (which is the letter C on the table). The Mass = 12.01 amu or grams and the atomic number is 6. They're on the periodic table too!



check this out for reference: http://www.dayah.com/periodic/Images/per鈥?/a>