Atomic Theory and Structure

The Theory of the Atom _________ __, a Greek teacher in the 4th Century B.C., first suggested the idea of the atom. _________ __, a Greek teacher in the 4th Century B.C., first suggested the idea of the atom. All matter is composed of tiny, _________ particles called _______All matter is composed of tiny, _________ particles called _______ t.com/content/radioactivity/democritus-lavoisier-dalton/&usg=__l- hTL60sR3IuOH7Z68HEc4nEp40=&h=126&w=195&sz=11&hl=en&start=3&um=1&tbnid=qyhFfwms7UcLvM:&tbnh=67&tbnw=104&prev=/images% 3Fq%3DDalton%2527s%2BAtom%26hl%3Den%26sa%3DN%26um%3D1http://images.google.com/imgres?imgurl= t.com/content/radioactivity/democritus-lavoisier-dalton/&usg=__l- hTL60sR3IuOH7Z68HEc4nEp40=&h=126&w=195&sz=11&hl=en&start=3&um=1&tbnid=qyhFfwms7UcLvM:&tbnh=67&tbnw=104&prev=/images% 3Fq%3DDalton%2527s%2BAtom%26hl%3Den%26sa%3DN%26um%3D1 Democritus indivisible atoms

In 1803, ____________ studied experiments and concluded that the properties of matter could be explained in terms of _____. In 1803, ____________ studied experiments and concluded that the properties of matter could be explained in terms of _____. John Dalton atoms

Dalton’s _____________ had 4 points Dalton’s _____________ had 4 points 1. Each ________ is composed of extremely small particles called atoms (which are indivisible). 2. All atoms of a given element are _______, but they differ from those of any other element. Atomic Theory element identical

3. Atoms are neither ________ nor ________ in any chemical reaction. 4. A given _________ always has the same relative numbers and kinds of atoms. Atomic Theory Continued… created destroyed compound

Dalton’s Model of the Atom He believed the atom was a solid sphere w.furryelephant.com/content/radioactivity/democritus-lavoisier-dalton/&usg=__l- hTL60sR3IuOH7Z68HEc4nEp40=&h=126&w=195&sz=11&hl=en&start=3&um=1&tbnid=qyhFfwms7UcLvM:&tbnh=67&tbnw=104&prev=/i mages%3Fq%3DDalton%2527s%2BAtom%26hl%3Den%26sa%3DN%26um%3D1

The Atom Is composed of an __________ is an atom. Is composed of an __________ is an atom. The atom is made up of three ___________ particles: ________, The atom is made up of three ___________ particles: ________, ___________ and __________ ELEMENT SUBATOMIC PROTONS NUETRONS ELECTRONS

Michael Faraday Michael Faraday Atoms contain particles that have an __________ charge Atoms contain particles that have an __________ charge electrical

Electron Discovered in 1897 by __________ Discovered in 1897 by __________ Has a _________ charge Has a _________ charge JJ Thomson negative

Thomson also thought in addition to the negatively charged electrons, there must be something with a __________ charge because the overall charge of the atom is ___________ positive neutral

Plum Pudding Model

Ernest Rutherford Performed Gold Foil Experiment in ______. Performed Gold Foil Experiment in ______. He shot _______ particles (very small, dense, fast and positively charged particles) at a thin layer of gold foil. He shot _______ particles (very small, dense, fast and positively charged particles) at a thin layer of gold foil alpha

Alpha particles source Gold foil Detector screen Alpha particles Because of Thomson’s Atom

But, what he found was this…

Most of the alpha particles went straight through but a tiny amount were deflected In the atom there was something dense enough to deflect the alpha particles = ________ Like this… nucleus

Importance of Rutherford’s Experiment 1. Showed most of the atom is made up of empty __________ 1. Showed most of the atom is made up of empty __________ 2. Proved the atom had a small, dense area in its center known now as the _____________ 2. Proved the atom had a small, dense area in its center known now as the _____________ 3. The nucleus has a _________ charge (must have __________ in it) 3. The nucleus has a _________ charge (must have __________ in it) nucleus positive protons space

Rutherford’s Atom

Other important discoveries…… Other important discoveries……

Neutron Discovered in 1932 by ____________ Discovered in 1932 by ____________ Has no charge (i.e. It is ______) Has no charge (i.e. It is ______) neutral James Chadwick

Proton Discovered in ______ by E. Goldstein Discovered in ______ by E. Goldstein Has a ________ charge Has a ________ charge 1886 positive

Bohr Model

Modern Atomic Structure The atom is made up of 2 parts/sections The atom is made up of 2 parts/sections (1) The _________ --- (in the center of the atom; contains protons and neutrons) (2) The _____________ --- (surrounds the nucleus) nucleus electron cloud Nucleus (protons and neutrons) Electrons cloud (electrons)

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The Atom The smallest particle of an ________ is an atom. The atom is made up of three _________ particles: _______, _________, and _______ element subatomic protonsneutrons electrons

ParticleCharge Location Mass (g) Mass (amu) Proton (P ) PositiveNucleus x 10 1 Neutron (N°) Neutral (No charge) Nucleus X 10 1 Electron (E ) Negative Around Nucleus x (0)

Protons

Overall Charge The overall charge of an atom is ____(neutral) The overall charge of an atom is ____(neutral) So, the number of protons must _______ the number of electrons So, the number of protons must _______ the number of electrons So, the atomic number also tells us the number of _______________in an atom So, the atomic number also tells us the number of _______________in an atom 0 equal electrons

Mass Number The mass of an atom The mass of an atom Measured in ________ Measured in ________ Equal to the total number of __________ and __________ Equal to the total number of __________ and __________ AMU’s protons neutrons

How to determine…….. 1) The number of protons = Look at ______________ 1) The number of protons = Look at ______________ 2) The number of electrons = Look at ______________(number of protons = number of electrons) 2) The number of electrons = Look at ______________(number of protons = number of electrons) 3) The number of neutrons = ___________ – atomic number 3) The number of neutrons = ___________ – atomic number atomic number Mass number

Practice Problems 1) Find the # of e -, p + and n 0 for sodium. (mass # = 23) 2) Find the # of e -, p + and n 0 for uranium. (mass # = 238) 3) What is the atomic # and mass # for the following atom? # e - = 15; # n 0 = 16 # e - = 15; # n 0 = 16

Ions When an atom loses or gains one or more ________, it acquires a net electrical charge and is called an ____. When an atom loses or gains one or more ________, it acquires a net electrical charge and is called an ____. 2 types of ions: 2 types of ions: 1) Anion 1) Anion 2) Cation 2) Cation electrons ion

Anions and Cations ____________: An ion that has more electrons than protons has a ___________ charge. **(Gained Electrons)** ____________: An ion that has more electrons than protons has a ___________ charge. **(Gained Electrons)** ____________:An ion that has fewer electrons that protons has a _____________ charge. ____________:An ion that has fewer electrons that protons has a _____________ charge. **(Lost Electrons)** **(Lost Electrons)** Anion negative Cation positive

Determining the Charge of an Ion # of protons - # of electrons # of protons - # of electrons

Ion Notation

Practice Problems 1) A neutral magnesium atom (atomic number 12) has 12 protons and 12 electrons. If the atom loses 2 electrons, what is the charge of the resulting ion? 2) How many electrons would be found in the ion O 2- ? 3) If an ion has 28 protons and 26 electrons, what is its charge? What is its symbol (including charge)?

Isotopes An isotope refers to atoms that have the same # of ______, but they have a different # of _______. An isotope refers to atoms that have the same # of ______, but they have a different # of _______. Because of this, they have different ____ #’s (or simply, different ______.) Because of this, they have different ____ #’s (or simply, different ______.) protons neutrons mass masses

Exm: (1) Carbon-12 & Carbon-13 (2) Chlorine-35 & Chlorine-37 (2) Chlorine-35 & Chlorine-37 (The # shown after the name is the mass #.) For each example, the elements have identical ______ #’s, but different _____ #’s For each example, the elements have identical ______ #’s, but different _____ #’s atomic mass

Isotopes cont… In nature, elements are found as a _______________ of all their isotopes In nature, elements are found as a _______________ of all their isotopes The isotopes are found in the same __________________ The isotopes are found in the same __________________ mixture percentage

More Practice Problems 1) Find the # e -, p + and n 0 for Xe ) Find the # e -, p + and n 0 for Cu 3) Write a shorthand way to represent the following isotope: # e - = 1 # n 0 = 0 # p + = 1 # e - = 1 # n 0 = 0 # p + =

Atomic Mass The atomic masses listed in the Periodic Table are a “_____________” of all the isotopes of the element. The atomic masses listed in the Periodic Table are a “_____________” of all the isotopes of the element. weighted average

Practice Problems (1) Mrs. Smith’s geometry semester grades are calculated using a weighted average of three category scores: Tests/Quizzes= 30% of your grade Homework/Participation=60% of your grade Semester Exam= 10% of your grade If a student had the following scores, what would they receive for the semester? If a student had the following scores, what would they receive for the semester? Tests/Quizzes= 80 (B-) Homework/Participation= 60 (D-) Semester Exam=65 (D)

Step (1): Multiply each score by the % that it is weighted. Step (2): Add these products up, and that is the weighted average! A “normal average” would be calculated by simply adding the raw scores together and dividing by 3… = 205 ÷ 3 = 68.3 = D +

(2) In chemistry, chlorine has 2 isotopes: Cl-35 (75.8% abundance) Cl-35 (75.8% abundance) Cl-37 (24.23 % abundance) What is the weighted average atomic mass of chlorine? (3) Oxygen has 3 isotopes: O-16 (99.76%) O-17 (0.037%) O-18 (0.2%) Estimate oxygen’s average atomic mass. +