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Periodic Table An atom refresher • Matter is anything that takes up space and has mass. • All matter is made of atoms • Atoms are the building blocks of matter, sort of how bricks are the building blocks of houses. • Who contributed to the atomic theory from ancient Greece to modern day? Scientist that contributed to the Atomic Theory include: • Democritus – “Atomos” • JJ Thomson – cathode ray tube, found electrons, Plum Pudding model • Ernest Rutherford – gold foil expt., found nucleus as a positive center • Neils Bohr – Bohr model with orbitals for electrons around the nucleus, like a planetary system • Schrodinger – said e- act as particles • Chadwick – found neutrons • Heisenburg – pulled together all & said there is an electron cloud model, quantum Atom • An atom has three parts: • Proton = positive • Neutron = no charge • Electron = negative • The proton & neutron are found in the center of the atom, a place called the nucleus. • The electrons orbit the nucleus. What are elements? • Elements are the alphabet to the language of molecules. • To make compounds, you must have elements. • Elements are made of atoms. While the atoms may have different weights and organization, they are all built in the same way. More about Elements.. • Elements are the building blocks of all matter. • The periodic table is a list of all of the elements that can build matter. It’s a little like the alphabet of chemistry. • The periodic table tells us several things… Families or groups Alkali Metals Alakaline Earth Metals Transition Metals Halogens Noble or Inert Gases Lanthinide Series Actinide Series What 2 main categories are on the periodic table? On your periodic table: • Number the TALL Columns 1-8 because these are called “representative elements” that the tall column number is the same for how many valence electrons exist on the outer most orbital Periodic Table Atomic Number: Number of protons and it is also the same number of electrons in the element. Symbol: An abbreviation for the element. Elements Name Atomic Mass/Weight: Number of protons + neutrons that exist in the nucleus. 8 O Oxygen 16 Using your periodic table • Find the following using your periodic table: Symbol Na Al Cr Bi Ra Name Mass # Atomic # protons electrons What is an isotope? • Isotopes are two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei • Examples: C-12 U-235 C-13 U-236 C-14 U-238 1. How many p+, e-, n0 exist in each isotope? 2. What is the element when it is 41 19 X? Shorthand Notation: Mass number Symbol Atomic number 35Cl 17 1. Write the shorthand notation for Al Cr Bi Ra 2. What do you use to tell the identity of an element? 3. What changes to result in a charge on an element? 4. What is an element with a charge called? ION is a charged element 1.Ions are a result of electrons being ________. 2. A positive charged element has ______ electrons & is called a ______. 3. A negative charged element has _____ electrons & is called a _____. 4. Draw the Bohr models of Na + Cl NaCl and show how electrons are transferred. Which part of the reaction is a cation?______ Which is an anion?_____ 5. Which element gives up electrons when lithium combines with fluorine to make lithium fluoride: Li + F LiF Li+1 + F-1 LiF Atom Models • There are two models of the atoms we will be using in class. • Bohr Model (orbitals around nucleus & show valence electrons only in outer orbital) • Lewis Dot Structure (only uses valence electrons around the symbol & we will do these at a later time) Bohr Model • The Bohr Model shows all of the particles in the atom. • In the center is the nucleus. • In a circle around the nucleus are the electrons. Electrons should have a minus sign or an e. e Electrons have special rules…. • You can’t just shove all of the electrons into the first orbit of an element. • Electrons live in something called shells or energy levels also referred to as orbitals. • Only so many can be in any certain shell. • The electrons in the outer most shell of any element are called valance electrons. Nucleus 1st shell 2nd shell 3rd shell 4th shell – if valence orbital then it can only hold a maximum of 8 electrons NOTE: Only when there is another orbital on the outside can the 3rd shell hold up to 18 e-, otherwise if this is the outermost orbital then it can only hold 8 electrons to obey the octet rule! So let’s try it…. • Draw the Bohr model for lithium: 3 Li Lithium 7 QUIZ on Friday, I can: (if absent be ready to take on Tuesday during Eagle Time) • Interpret the arrangement of the Periodic Table, including groups names and periods, for orbitals & number of valence e-, & to know that properties are similar for elements in a group • Describe the structure of atoms, including the masses, electrical charges, and locations of protons, neutrons, and electrons • Identify that protons determine an elements identity and valence electrons determine its chemical properties, including reactivity • Describe the historical development of atomic theory & periodic table – who did what. On the Quiz, I can: • Understand the experimental design and conclusions used in the development of modern atomic theory, including scientists’ contributions • Determine the number of protons, neutrons, electrons, and charge of a neutral, ion, or isotopic element by using isotope notation. Who did what? (Match them up) • I used the Gold Foil • Dimitri Mendeleev Experiment to discovered + charged nucleus & my model • Democritus & the “planetary system” Aristotle • I was the first to call the atom • as atomos • • I worked with organizing the • periodic table using atomic numbers. • • I discovered the electron using a cathode tube & my atom model is called the “plum pudding” model Niels Bohr John Dalton Henry Moseley Ernest Rutherford • J.J. Thomson Continue with Who did what? • I organized the 1st periodic table using atomic masses. • Dimitri Mendeleev • Democritus & Aristotle • My atomic model helped • describe the orbits of electrons, has been called • the planetary model & is • still used today. • • I believed that atoms could not be broken down • Niels Bohr John Dalton Henry Moseley Ernest Rutherford J.J. Thomson Your activity… • Make a periodic table chart on your paper of the first three periods only & draw the Bohr model for the first 18 elements. • Use the