Atomic Structure
AZ State Standards Concept 1: Structure and Properties of Matter Understand physical, chemical, and atomic properties of matter. PO 6. Describe the following features and components of the atom: protons neutrons electrons mass number and type of particles structure
Content Objectives SWBAT describe the charge, size, and location of subatomic particles that make up the atom and will draw different elements with the proper number of each particle.
Proton Atomic Particles
Atomic Particles Proton Neutron N Protons and Neutrons together are called Nucleons
Atomic Particles Proton Neutron N Electron - Protons and Neutrons together are called Nucleons
Atomic Number is the number of Protons
Atomic Number is the number of Protons Atomic Mass is the # of Protons and Neutrons together
Proton Positively charged particle Resides in the nucleus Weighs 1 Atomic Mass Unit (AMU) Repel other protons The number of protons determines the element number.
Proton Positively charged particle Resides in the nucleus Weighs 1 Atomic Mass Unit (AMU) Repel other protons The number of protons determines the element number. Which element would this be?
Proton Positively charged particle Resides in the nucleus Weighs 1 Atomic Mass Unit (AMU) Repel other protons The number of protons determines the element number. Which element would this be? Carbon
Too Many Protons Protons repel each other due to the electromagnetic force If an element has too many protons, it will be unstable and will break apart.
Too Many Protons This is why all elements over #82 Lead are radioactive! In addition, none over #94 Plutonium exist naturally.
Neutron A Neutron has a neutral charge N Neutrons weigh 1.001 the mass of a proton Resides in the nucleus It does not affect the elemental or chemical properties of the atom
Neutron A Neutron has a neutral charge N Neutrons weigh 1.001 AMU Resides in the nucleus It does not affect the elemental or chemical properties of the atom It does provide additional nuclear force to
Isotopes Isotopes result from different numbers of neutrons in an element Isotopes are chemically the same N N N N N N N N N N N N N N
Isotopes Isotopes result from different numbers of neutrons in an element Isotopes are chemically the same They only differ in their mass and their nuclear stability N N N N N N N N N N N N N N Carbon-12 C 12 Carbon-14 C 14
Atomic Mass Atomic mass is the mass of all the nucleons (Protons and Neutrons). You can ignore electrons because they are so tiny To figure out the number of neutrons, just go Atomic Mass- Atomic # = Neutrons He 4-2 = 2 neutrons He 2 4 Helium Pb 207-82 = 125 neutrons Pb 82 207 Lead
Average Atomic Weight It is the average of all known isotopes on Earth for an element Lead Pb 82 204 Lead Pb 82 206 Lead Pb 82 207 Lead Pb 82 208 1.4% 24.1% 22.1% 52.4%
Average Atomic Weight It is the average of all known isotopes on Earth for an element Lead Pb 82 204 Lead Pb 82 206 Lead Pb 82 207 Lead Pb 82 208 1.4% 24.1% 22.1% 52.4% Calculate the average atomic weight for Lead Lead Pb 82?
Average Atomic Weight Lead Pb 82 204 Lead Pb 82 206 Lead Pb 82 207 Lead Pb 82 208 1.4% 24.1% 22.1% 52.4% Calculate the average atomic weight for Lead (204*.014) (206*.241) (207*.221) (208*.524) = 207.24 Pb 82 207.2 Lead
Strong Nuclear Force The strong nuclear force is the force that holds the nucleus together. All Nucleons are attracted to each other. Because protons repel each other (electromagnetic force), the presence of Electromagnetic Force neutrons helps bind the nucleus together. Strong Nuclear Force N Strong Nuclear Force N N Strong Nuclear Force
Atomic Stability The more protons there are, the more neutrons are necessary to stabilize the nucleus. Note that Helium 4 has 2p/2n ratio (1:1) Lead 207 has 82p/125n ratio (1:1.5) He 2 4 Helium Pb 82 207 Lead
Atomic Stability The more protons there are, the more neutrons are necessary to stabilize the nucleus. Radioactive Isotopes
Electrons Electrons are negative particles - Electrons weight 0.001 AMU They reside outside the nucleus They usually match the number of protons to make a neutral atom
What is a Neutron Anyways? OK, so you ve heard that Neutrons are neutral and weigh 1.001 AMU Do you notice any pattern here?
What is a Neutron Anyways? Think of a Neutron as a Proton and Electron stuck together.
This actually changes the element it is! Beta Decay? When an isotope has too many neutrons, a neutron will emit a β-particle (which is basically an electron) This causes the neutron to change from neutral to positive (i.e. a proton).