STOICHIOMETRY EXAM Thursday & Friday 10/01-10/02/2015 TRUTH!
AGENDA Finish Stoichiometry Unit Exam (45 minutes MAX) Begin Topic 2: Atomic Structure & Project Introduction Groups assigned today
GROUPS You will be assigned to TWO groups: One is your expert group The second is your home group
ATOMIC STRUCTURE GOALS: to teach the other members of their group a sub concept of atomic structure. Atomic number, Mass number, Isotopes, and Nuclear atom learn how to use the periodic table as an effective teaching tool
EXPERT GROUPS These are the groups you will create what you are teaching - you will be working together for the duration of the project You are responsible for creating a handout that you will all use to teach your lesson You must identify roles and duties of each individual in your group You need to make sure you ALL have the SAME content to teach but are free to choose different methods to teach your lesson
HOME GROUPS These are the groups you will come back to and teach what you ve become a master in! You will only see them once! You are responsible for creating a handout that your home group will fill out WHILE you teach You must present the information in a visible/ tangible way (no just verbal lessons) i.e. have them build something, draw something, make a presentation, note taker, etc.
EXPERT GROUPS Member A - Atomic Number Expert. This person is responsible for teaching the other members of the group what Atomic Number means. Explain how atomic number is found using the periodic table. These students also realte atomic number to number of electrons and protons. Member M - Mass Number Expert This person is responsible for teaching the other members of the group what Mass Number means. They will explain how to find mass number and how it relates to any subatomic particles (proton and neutron).
EXPERT GROUPS Member I - Isotope Expert This person is responsible for teaching the other members of the group what an Isotope is. They will explain how isotopes of one element are the same and how they are different. They will also draw pictures of nuclei of different isotopes of the same element. Member N - Nuclear Atom Expert This person is responsible for teaching the other members of the group how to show Atomic Number and Mass Number using the Nuclear Atom shorthand and the Isotope shorthand.
TIPS/ADVICE Be creative! Work with everyone in your expert group to create something you can all take back to your home groups and teach effectively. Atomic # & Mass # groups should become familiar with the location of atomic numbers and atomic weights on the periodic table Isotope group should become familiar with how atomic weight is a weighted average of atoms with different mass numbers but the same atomic number Nuclear atom experts should be able to relate how information is displayed on the periodic table to how it can be interpreted using the nuclear notation model.
Atomic Structure The nuclear atom Electron Configuration Ms. Thompson - Honors Chemistry Wooster High School
Topic 2.1 The nuclear atom Understand that the atom is made up of protons, neutrons, and electrons Define mass number, atomic number, and isotope Work out the number of protons, neutrons, and electrons in atoms and ions Discuss the properties of isotopes Calculate relative atomic masses and abundances of isotopes Understand that a mass spectrometer can be used to determine the isotopic composition of a sample
The nuclear atom Subatomic particles and descriptions of the atom Of all the elements, only 92 are naturally occurring, the others are synthetic Make up all that we know in our E N T I R E U N I V E R S E List of 92 Naturally Occurring Elements
The nuclear atom Subatomic particles and descriptions of the atom Atoms consist of three types of subatomic particle: proton neutron (discovered by British physicist James Chadwick, 1932) electron Masses are in atomic mass units (amu) 1 amu = 1.660539 x 10-24 g Subatomic Particle Charge Mass/amu Location proton +1 ~1 nucleus neutron 0 ~1 nucleus electron -1 5 x 10-4 outside nucleus in electron cloud
The nuclear atom Subatomic particles and descriptions of the atom The atomic number, Z Atoms each have their own unique atomic number, Z The atomic number is the number of protons in the nucleus of the atom of an element. In a neutral atom (no overall charge) the number of electrons is equal to the number of protons. Z for oxygen is 8, oxygen has 8 protons and 8 electrons (-8)+(+8) = 0 (neutral) number of protons in an atom = number of electrons
The nuclear atom Subatomic particles and descriptions of the atom The mass number, A The mass of the atom comes from the nucleus, which contains the protons and neutrons. The mass number, A, is the number of protons + number of neutrons Z for fluorine, F, is 9, fluorine has 9 protons and 9 electrons A for fluorine-19 is 19. Therefore, fluorine has 19-9=10 neutrons Mass number (A) is the number of protons plus neutrons in the nucleus of an atom
The nuclear atom Subatomic particles and descriptions of the atom To calculate the number of neutrons: Number of neutrons in an atom = mass number - atomic number
Practice Problem... I Do... Calculate the number of protons, neutrons, and electrons for the following elements: Sodium (Na), Iron (Fe), Bromine (Br)
Practice Problem... We Do... Identify which elements are listed below: Element # Protons # Electrons # Neutrons 12 12 12 34 34 44 55 55 77
Practice Problem... We Do... Identify which elements are listed below: Element # Protons # Electrons # Neutrons Magnesium (Mg) 12 12 12 Selenium (Se) 34 34 44 Cesium (Cs) 55 55 77
Practice Problem... You Do... Fill in the table below - show work in your notebook (left side!) Element # Protons # Electrons # Neutrons 19 Bismuth (Bi) 80
The nuclear atom Subatomic particles and descriptions of the atom Ions are charged particles that are formed when an atom loses or gains an electron(s). Cations are positively charged (meaning they lost electrons) There are more protons (+) than electrons (-) Anions are negatively charged (meaning they gained electrons) There are more electrons (-) than protons (+)
The nuclear atom Subatomic particles and descriptions of the atom The nuclear notation includes both A and Z for a particular element X and is represented like this: A X Z Isotopes are different forms of the same element but have 3 different number of neutrons 1H (tritium) (different mass numbers, A) 1 proton, 1 electron, 2 neutrons 2 Have same chemical properties 1H (deuterium) (react in exact same way) but 1 proton, 1 electron, 1 neutron 1 different physical properties (i.e. 1H (hydrogen) different melting points or 1 proton, 1 electron, 0 neutrons boiling points) Hydrogen has three isotopes:
The nuclear atom Why do isotopes react in the same exact way???? Turn to your partner and discuss why you think that is the case? Isotopes react the same way because they have the same number of electrons and electrons are what is responsible for all chemical reactions! Chemical reactions depend only on the number and arrangement of electrons - not the composition of the nucleus!
The nuclear atom Relative atomic masses Because multiple isotopes can exist for one element, it is most convenient to quote an average mass for an atom relative atomic mass (Ar) The relative atomic mass (Ar) for an element is based on taking the average of all the masses of the isotopes in a naturally occurring sample of the element This
The nuclear atom Mass spectrometer
Mass Spectrometer Process vaporization ionization acceleration deflection detection Equipment vaporizer ionizer accelerator deflector detector Details the atom is changed into a gaseous state the atom is bombarded by a beam of electrons to form positive ions the positive ions will pass through an electrical field where it will be accelerated the positive ions will pass through a magnetic field where the lighter ions will be deflected more than the heavier ions the difference ions will be detected
Practice Problem... I Do... Boron has two naturally occurring isotopes with the natural abundances shown below: Isotope Natural Abundance/% 10 B 19.9 11 B 80.1 Calculate the relative atomic mass of boron: relative atomic mass = (10 x 19.9 ) + (11 x 80.1 ) = 10.8 100 100
Practice Problem... We Do... Rubidium has a relative atomic mass of 85.47 and consists of two naturally occurring isotopes, 85 Rb (u=84.91) and 87 Rb (u=86.91). Calculate the percentage composition of these Ar = 85.47 = isotopes in a naturally occurring sample of rubidium. 84.91x + 86.91(100-x) 100 85.47 x 100 = 84.91x + 86.91(100-x) 8547 = 84.91x + 8691-86.91x -2.00x = -144 x = 72.00 The sample contains 72.00% 85 Rb and 28.00% 87 Rb
Practice Problem 20 mins... You Do... Work with a partner and answer the following 45 40 Hint: 27 & 71 = peak heights question: 35 Deduce the relative atomic mass of the element X from its mass spectrum (right) and identify X from the periodic table. Hint: X-69 and X-71 relative abundance 30 25 20 15 10 5 0 69 71 0 20 40 60 80 100 m/z
Topic 2.1 The nuclear atom Atoms contain a positively charged dense nucleus composed of protons and neutrons (nucleons). Negatively charged electrons occupy the space outside the nucleus. The mass spectrometer is used to determine the relative atomic mass of an element from its isotopic composition.