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Chapter 4 Atomic Structure Section 4-1 Objectives • Describe ancient Greek models of matter • List the main points of Dalton’s atomic theory and describe his evidence for the existence of atoms • Explain how Thomson and Rutherford used data from experiments to produce their atomic models What is the derivation of the word “atom” ? • “a” – not • “tomos” - cutting • Matter can only be subdivided as small as an elemental particle:___________ Democritus • About 400 BC • World is made of 2 things – 1) -____________ – 2) _____________ called “atoms” Aristotle • Matter is continuous and_______MADE OF ATOMS • few believers in atoms for nearly 2,000 yrs • WHY????????????????? Dalton’s Theory __________ produced the theory that all matter is made up of individual particles called_______, which cannot be divided. Main Points to Dalton’s Theory • All _______ are composed of atoms • All atoms of the same element have the _______ mass, and atoms of different elements have _______ masses • _________ contain atoms of more than one element • In a particular compound, atoms of different elements always_________ in the same way. Early Research on Atomic Particles • Eventually__________were discovered to Dalton’s Atomic Theory…….. J.J Thompson • Created ____________ Experiment Cathode Ray Studies of the mid 1800’s What did these observations mean? • Glowing______ in cathode tube was made of particles • Particles that composed cathode rays are negatively charged called__________ • Thomson’s experiments provided the first evidence that atoms are made of even smaller _________ Thomson’s Model • • • • Called “_____________” Looks like chocolate chip ice cream Chocolate is negative particles Vanilla ice cream is positively charged matter Teacher Demo Investigating Charged Objects • Pg 102 Rutherford’s Atomic Theory • The______________ experiment Observations • Most__________particles passed through the gold foil • About 1 in 8,000 particles bounced almost straight________ Discovery of the Nucleus • Rutherford’s experiment discovered the ____________ • Nucleus is a dense, positively charged mass located in the _________ of the atom. • According to Rutherford’s model, all of an atom’s_________charge is concentrated in its nucleus. Beaker Breaker 1. The gold foil experiment was done by _________ 2. The cathode ray tube experiment was done by ___________ 3. Who discovered the nucleus?____________ Section 4-2 The structure of an Atom Objectives • Identify three subatomic particles and compare their properties • Distinguish the atomic number of an element from the mass number of an isotope, and use these numbers to describe the structure of atoms Definitions • Use your book to define the following 2. Electron- 3. Neutron- 4. Atomic number- 5. Mass Number- 6. Isotopes- 1. Proton – Properties of Subatomic Particles • ________, ________, and_______ are subatomic particles Protons • A _________is a _________ charged subatomic particle that is found in the nucleus of an atom • Each proton is assigned a_______charge • Some nuclei contain more than 100 _________ Electrons • An________ is a___________ charged subatomic particle that is found in the space outside the nucleus. • Each electron has a charge of_____. Neutrons • A________ is a________ subatomic particle that is found in the nucleus of an atom. • It has a_______almost exactly equal to that of a proton • James_______designed an experiment to show that neutrons exist. Comparing Subatomic Particles • Protons, electrons, and neutrons can be distinguished by_______, _______ and_______ in an atom. • Protons and neutrons have almost the ______mass • Electrons have a charge that is_________ of the charge of a proton • Protons and neutrons are found in the _______, but electrons are found in the space outside the nucleus. Atomic Number • The_____________ of an element equals the number of_________ in an atom of that element • Atoms of_________elements have different numbers of protons. • Atomic number also tells you the number of _________ • Ex: Sulfur atomic number = _____ • Ex : Carbon (C ) atomic number =_____ Mass Number • The__________ of an atom is the sum of the ________ and _________in the nucleus of that atom • Ex: Aluminum has____protons and_____neutrons has a mass number of ______ • If you know the atomic number and the mass number of an atom, you can find the number of neutrons by_________. • Mass number – Atomic number = Number of neutrons Isotopes • _________ of an element have the same _____ number but different _____ numbers because they have different numbers of _______. • Ex Oxygen -___ (protons and 8 neutrons) Oxygen – ___ ( 8 protons and 9 neutrons) Oxygen -___( 8 protons and 10 neutrons) Beaker Breaker • A __________is a neutral subatomic particle that is found in the nucleus • An electron has a _________charge • ______and ________are located in the nucleus, while_______are located outside the nucleus Section 4-3 Modern Atomic Theory Objectives • Describe Bohr’s model of the atom and the evidence for energy levels • Explain how the electron cloud model represents the behavior and locations of electron in atoms • Distinguish the ground state from excited states of an atom based on electron configurations Bohr’s Model • Model of atom looks like a_____________ with planets revolving around a sun • Model focused on _________ Bohr’s Model and energy levels • The possible energies that electrons in an atom can have are called____________. • Energy levels are like _______ on a staircase, an electron_______exist between energy levels • An electron in an atom can move from one energy level to another when the atom_____ or ________energy Evidence for Energy Levels • Scientist can measure the energy gained when electrons ________ energy and move to a _______ energy level. • They can measure the energy______ when the electron returns to a ________ energy level Flame Test Lab • Read page 116 “evidence for energy levels” in the book Question : How do these substances produces light of different colors? Electron Cloud Model • An electron ________ is a visual model of the most likely_________for electrons in an atom. • Scientists use the electron cloud model to describe the possible locations of _______ around the __________ • Ex: ________ on a propeller of an airplane Atomic Orbitals • An _______ is a region of space around the nucleus where an electron is likely to be found • An electron cloud is a good approximation of how electrons ________ in their orbitals. • Higher energy levels have more than one ________ Modern Atom 1. Louis de Broglie – proposes that moving particles like electrons have some properties of ___________. 2. Erwin Schrodinger develops mathematical__________ to describe the motion of electrons in atoms (electron cloud). 3. James Chadwick- confirms the existence of_________in the nucleus, which have no charge Drawings of Atoms Electron Configurations • An electron _________ is the arrangement of electrons in the orbitals of an atom • The most stable electron configuration is the one in which the electrons are in orbitals with the_________ possible energies • When all the electrons in an atom have the lowest possible energies, the atom is said to be in its _____________.