 Introduction to the Atom Modern Atomic Theory Subatomic Particles Isotopes Ions Essential Standards and objectives: Analyze the structure of atoms, isotopes, and ions Analyze an atom in terms of the location of electrons Explain the emission of electromagnetic radiation in spectral form in terms of the Bohr model Explain the process of radioactive decay using nuclear equations and half-life Analyze quantitatively the composition of a substance. (Introduction to moles)

Atoms: The Building Blocks of Matter Unit 2

Homework for the Bohr Model – should look like this Group 1 Group 2 Groups 2-12 Group 13 Group 14 Group 15 Group 16 Group 17 Group 18 P1 P2 P3

The Atom: Smallest particle of an element that retains the chemical properties of the element. Essential Questions: What is an atom? What is its structure? What determines properties of an element??

Atoms act in orderly, predictable ways.

Modern Atomic Theory 1. All matter: 2. Atoms of a given element: 3. Atoms cannot be created nor destroyed in: 4. In chemical reactions, atoms are

Atomic Theory (cont.) 5. To form compounds: Law of Definite Proportions Law of Multiple Proportions

Atomic Structure Subatomic LocationCharge Amu Importance Particle

Atomic Mass Unit AMU

Designation of Atomic Structure  Atomic number (Z): On the Periodic Table:  Mass number (A): On the Periodic Table:

Review: What is Z? What is A? Determine the number of protons, neutrons, and electrons. 31 Ga Gallium Ge Germanium 72.61

Video: Atomic structure & introduction to isotopes

Isotopes

Isotopes:  Atoms of an element with different masses Naturally occurring Some are stable and some are radioactive (unstable)  Isotopes of an element have the same number of ___________ and a different number of ______________.

Identifying Isotopes  Isotope Notation On the Periodic Table, the number with the Decimal point is:

Atoms of the Same Element

Atomic Mass  Weighted Average Mass of isotopes  Based on the percentage of each isotope present.

Grades are often computed using a weighted average.  Suppose that homework counts 10%, quizzes 20%, Labs 10% and tests 60%.  If: homework grade is 92 quiz grade is 68 lab grade is 88 test grade is 81 What’s the overall grade?

Practice  Atomic Structure Identify the number of proton, neutron, & electrons of an atom of a specific element Rounding the atomic mass on the Periodic Table gives the mass of the most common isotope  Atomic Number & Isotopes Correct symbol: A & Z Complete the table Complete the questions.

Practice:  Find the Average Atomic Mass Nucleus of each atom is represented Graphic below #4 - explains #5-7  Isotopes: Atomic Number & Mass Number Determine based on the chart – not the PT 2 Isotope notations  Element – A (X-A) AZXAZX

Find Average Atomic Mass

Atomic Number & Isotope

Isotopes: Atomic Number & Mass Number ElementIsotope Symbol Atomic Number Z Mass Number A # of protons # of neutrons # of electrons

Stable Isotopes - frequency  pertable/PTFRAME.HTM pertable/PTFRAME.HTM

What is the atomic mass of Nitrogen given:  N-14 is 99.64% of all nitrogen  N-15 is 0.36% of all nitrogen

What is the atomic mass of Indium if:  In-113 is 4.24%  In-115 is 95.72%

Calculate % Abundances from Masses  Requires the use of 2 equations and 2 unknowns. Isotope 1(X) + Isotope 2(Y) = Atomic Mass X + Y = 1 Substitute and solve for X or Y!

What are the percent abundances of Vanadium if  V-50 + V-51 = amu

What are the percent abundances for Gallium if:  Ga-69 + Ga-71 = 69.72

Atom: Scanning Tunneling Microscope

Study of atomic particles

Scanning Tunneling Microscrope

Development of the Atomic Theory  Essential Question: Why do elements have different properties?

Development of the Modern Atomic Model Here are several models of the atom as they were developed in history:

Ancient Question

Atomic investigation

Bohr

Quantum Model  Electron Cloud model of the atom

Representing atoms with the Bohr Model

Bohr Model – Simplified but Useful Model Group 1 Group 2 Groups 2-12 Group 13 Group 14 Group 15 Group 16 Group 17 Group 18 P1 P2 P3

Bohr Model & the Periodic Table Making Conclusions Compare and Contrast Why are elements placed in a group (column)? Why are elements placed in a period (row?)

Changing An Atom Changing an Atom

Ions  Atoms can lose or gain electrons when bonding to make ionic compounds  We keep track of the number of electrons that can be lost or gained with oxidation numbers (also known as charges)  Ions are charged particles –when an atom has too many or too few electrons to be neutral No change to the nucleus Proton and neutrons stay the same number.

Ions – Charged Particles 7. When atoms of elements form ions (__________ __________, they must either __________ or _______ valence electrons. Gain/lose? Charge Ion type? Metals Non-metals

Why are ions important?  The ___________________ charged particles are like a magnet.  Therefore, they are strongly held together in an ______________ _____________ forming an _____ ________________.

Representing atoms with the Bohr Model

Ions Lithium atom - Lithium ion Ion Symbolp+nºe- Fluorine atom Fluorine ionp+nºe-

Ions and Charge Net electric charge Note change 8

Ions and Charges for Representative Elements (Oxidation number keep track of electrons)

Ion Making

Making an ion of an alkali metal, First column in the periodic chart, Leaves all the ions with a plus one charge And they’re all a whole lot smaller than they were before.

Second column over, Alkaline earths, Loses 2 electrons easily, So their ions all have a plus 2 charge, And they’re smaller than their neighbors to the left.

Next door, aluminum, the 3 rd step over has 3 electrons It’d like to have removed. When they are gone, it has a +3 charge, And, by gosh!, It’s even smaller than the “lefter” two.

But add one electron To the halogen group, So they all have a Negative one charge. They get 8x bigger than They were before. Puffed up, very large.

Sulfur and oxygen need 2 electrons to give each a full and complete electron shell. Thus, minus 2 is their ionic charge. And they’re a little larger Than the “Hal-ions”.

Add three electrons to the nitrogen group. So that group has a triple minus charge. And the pattern we see makes it very clear. Negative ions are large!

Mole  Resources for students 

Nuclear Chemistry

Neutron to Proton Ratio

Types of Radiation

Alpha Decay

Beta decay

Gamma Decay

Radiation Strength

Nuclear Equations H Be ---> 6 3 Li + ? Al He ---> P + ? Mg  Mg + ? U  Th + ? C  0 -1 e + ? Pu He  Cm + ? Nuclear Equations Practice Website

Half-life  Measure of Radioactive decay rate.  Measured as the time it takes for ½ of a sample of radioisotope’s nuclei to decay into its products.

Half Life Decay of a radioisotope Number of Half-Lives Elapsed timeAmount remaining g 11.5 year50 g 23 years25 g years12.5 g

Half Life Problems  How much of a 100g sample of an unstable isotope remains after 25 years if the half life is 5 years? 3.1 g

Half Life Problems  How much of a 60g sample of an unstable isotope remains after 2 days if the half life is 12 hours? 7.5 g

Half Life Problems  How much of a 20 g sample of an unstable isotope remains after 6 sec if the half life is 0.5? g

Atomic Nucleus (also known as nuclide)  Mass  Energy  Volume

Radioactive Isotopes A radioactive isotope has an unstable nucleus that undergoes spontaneous changes. - Emits particles and energy - Transmutates into another element

Particles emitted from a radioactive isotope Type Symbol Charge Mass

Nuclear reactions Total number of atomic numbers and the total mass numbers must be equal on both sides of the equation. Examples:

Radioactive decay No 2 radioactive isotopes decay at the same rate. Therefore, decay rate can be used to identify the isotope. Decay is measured by half life.

Fission and Fusion

Origins of Element

Got Calcium  Where are most elements created?  When was H and He created?  What elements are made by small stars?  What additional elements are made by large stars?  What elements are made by supernovae (large exploding stars)?

Teachers' Domain: The Origin of the Elements

Teachers' Domain: The Elements: Forged in Stars