Atomic Structure

Atoms are mostly empty space Comprised to two main parts What is in an Atom? Atoms are mostly empty space Comprised to two main parts Nucleus – center portion containing protons and neutrons Electron Cloud – outside orbitals where electrons surround the nucleus.

What Is in an Atom? What is the difference between protons, neutrons, and electrons? The three main subatomic particles are distinguished by mass, charge, and location in the atom. Particle Location Charge Mass “Job” Proton Nucleus +1 ~1amu Determines identity of element Neutrons Supplies proper mass to hold nucleus together Electrons Electron Cloud -1 ~0 amu Determines bonding and reactivity

Atomic Number The Atomic Number is found in the top corner of each periodic square. Each element has its own Atomic Number - Atomic Number: the number of protons in the nucleus of an atom. The number of Protons identify the atom. Change the atomic number and you have a new element!

Average Atomic Mass It is the decimal at the bottom of the squares. It represents the average mass of all the atoms that make up this element.

Mass Number The mass number equals the total number of subatomic particles in the nucleus. #Protons + #Neutrons = Mass Number

What is the atomic number for: Chlorine Krypton Calcium Nitrogen What subatomic particle does the atomic number represent?

What about the other particles? We know how to get the number of Protons – Right? Atoms are neutrally charged. For that to occur the positive charges are canceled out by the negative charges. What does that mean about the total number of Protons and Electrons?

What about the other particles? What does the mass number represent? Where can we always go to get the number of Protons? So if we know the total number of particles in the nucleus, and we know how many protons there are, can we solve for neutrons?