Atomic Structure

Atomic Structure: Location: Where it is on the atom Charge: Electric charge (positive, negative or neutral) Mass: how big or small it is

Parts of the Atom: NUCLEUS The small center part of the atom that contains the neutrons and protons from Greek “karyon”, meaning kernel Protons and neutron are packed very tightly! The density is the same as having the entire mass of the sun squeezed into Chicago!

Parts of the Atom: ELECTRON CLOUD The large region around the nucleus that contain the traveling electrons 100,000 times larger in diameter than the nucleus! Impossible to determine the exact location of an electron within the cloud.

Parts of the Atom: PROTON Location: the center of the atom Charge: positive Mass: About 1 a.m.u, almost 2000 times larger than the electron, slightly smaller than the neutron PROTON From Greek “Protos” meaning first From suffix “ion” meaning subatomic particle

Parts of the Atom: NEUTRON Location: the center of the atom Charge: neutral Mass: about 1 a.m.u., almost 2000 times larger than the electron, slightly larger than the proton NEUTRON From the noun “neutral” From suffix “ion” meaning subatomic particle

Parts of the Atom: ELECTRON Location: the outer part of the atom, surrounding the nucleus Charge: negative Mass: almost 0 a.m.u., almost 2000 times smaller than the proton and neutron. ELECTRON From the word “electric” From suffix “ion” meaning subatomic particle

Comparing Locations: Electrons are on the outside of the atom. They spin around the nucleus in an electron cloud. The protons and neutrons are packed tightly together in the center of the atom. The space between the electron cloud and nucleus is huge! If the nucleus was the size of a golf ball, the electron cloud would be 1.5 miles away!

Comparing Charges: Electrons have a negative charge, protons have a positive charge and neutrons have no charge.

Comparing Mass: Protons and Nuetrons are almost 2000 times larger than electrons Electron (so tiny, you can’t see it) If a proton was the size of the blue sphere on the left, then the electron would be one pixel of the screen—so small, that you can’t see it! Click here to see website showing this.

Particles in various combinations Getting Smaller…. We now know that matter is made up of even smaller matter: Particles in various combinations Quarks Leptons up charm strange top bottom muon tau electron neutrino muon neutrino tau neutrino electron down We often learn of the periodic table of the elements in chemistry class. These 100+ chemical elements are billed as the fundamental building blocks of all matter. But that’s only partially correct. The atoms are not fundamental in the sense of being indivisible. In fact they are composites of much smaller particles. Today we know there are 12 fundamental particles – the particle physicists call this periodic table the “Standard Model” of particle physics. All matter is in fact made of these 12 particles. *Taken from powerpoint presentation: http://www.esi.utexas.edu/outreach/ols/lectures/Kopp/

Up and Down Quarks 3 quarks (up + up + down) make up a proton 3 quarks (down + down + up) make up a neutron electron This diagram shows how three quarks (up+up+down) make up a proton, and three quarks (down+down+up) make up a neutron. An atom consists of a nucleus made of protons and neutrons, and as shown in the diagram, the nucleus is orbited by electrons. *Taken from powerpoint presentation: http://www.esi.utexas.edu/outreach/ols/lectures/Kopp/ proton neutron

Bohr Model of a HELIUM ATOM + N - proton electron neutron Shell Question: What are some limitations of this model? Answer: Electrons are too large and not in an electron cloud, electrons are too close to the nucleus.

ATOMIC STRUCTURE Particle Charge Mass Location proton + ve charge 1 nucleus neutron No charge 1 nucleus electron -ve charge nil shell

ATOMIC STRUCTURE Electrons are arranged in Energy Levels or Shells around the nucleus of an atom. first shell a maximum of 2 electrons second shell a maximum of 8 electrons third shell a maximum of 8 electrons

Nucleus Contains protons and neutrons 1st shell Can hold up to 2 electrons 2nd shell Can hold up to 8 electrons 3rd shell Can hold up to 8 electrons Adapted from http://www.sciencespot.net/Media/atomsfam.pdf

Be 4 9.012 Beryllium Analyzing Elements on the Periodic Table Atomic number 4 Be the number of protons in an atom Element Symbol 1, 2 or 3 letters. First letter always capitalized, second always lower case. 9.012 Atomic Mass the number of protons and neutrons in an atom Beryllium Element Name * Number of electrons = number of protons * Number of neutrons = Atomic Mass (rounded to nearest) – Atomic Number

Li So let’s try it…. Lithium How to draw a Lithium atom 3 7 First, look at the Periodic Table Second, determine the number of protons (Look at the atomic number) Then determine the number of neutrons (Atomic mass – atomic number) Then determine the number of electrons (Look at the atomic number) 3 Li Lithium 7 Created by G.Baker www.thesciencequeen.net

Li Lithium Protons = 3 3 7 Electrons = 3 Neutrons = 4 - + + + - - Electrons = 3 2 in the 1st shell, 1 in the 2nd shell Neutrons = 4 (7-3=4) Created by G.Baker www.thesciencequeen.net