Investigation III: A Particulate World Alchemy Unit Investigation III: A Particulate World Lesson 1: Pudding and Clouds Lesson 2: Building Atoms Lesson 3: Subatomic Heavyweights Lesson 4: Life on the Edge Lesson 5: Shell Game Lesson 6: Go Figure Lesson 7: Technicolor Atoms

Alchemy Unit – Investigation III Lesson 1: Pudding and Clouds

ChemCatalyst In the 5th century BCE a Greek philosopher named Leucippus and his student, Democritis, stated, “All matter is made up of particles that cant be divided called atoms.” What do you think atoms are? Unit 1 • Investigation III

The Big Question How have chemists thought about the atom through history? Unit 1 • Investigation III

You will be able to: Describe some models of an atom and explain how they differ. Unit 1 • Investigation III

Notes Atoms are extremely small particles, which cannot be seen, even with microscopes. All matter is made up of atoms. Scientists have created models to describe atoms. Models are similar to theories, but often include a picture or physical representation. (cont.) Unit 1 • Investigation III

As new evidence is gathered, models are refined and changed. (cont.) Scientific evidence is a collection of observations that many people have made. Everyone agrees on the same collection of observations. When a model is supported by scientific evidence it is often accepted by the scientific community. As new evidence is gathered, models are refined and changed. Unit 1 • Investigation III

Parts of the Atom A proton is a positively charged particle that exists in the nucleus. A neutron is a neutral particle with no charge on it that exists in the nucleus The electron is a negatively charged particle that exists in an electron cloud around the nucleus. (cont.) Unit 1 • Investigation III

The Nucleus An atom is mostly empty space. There is the nucleus, which is located in the very center of the atom. The nucleus is very small. . The nucleus is also very dense and consists of two types of particles—neutrons and protons. (cont.) Unit 1 • Investigation III

A cloud around the nucleus where the electrons can be found. Electron Cloud A cloud around the nucleus where the electrons can be found. Unit 1 • Investigation III

Notes (cont.) Unit 1 • Investigation III

Activity Purpose: This lesson will introduce you to various models for the atom that have appeared over the past two hundred years. The descriptions of five models of the atom are on a separate handout. (cont.) Unit 1 • Investigation III

Theories of the Atom The History of the Atom

Atoms can not be divided into smaller pieces John Daltons Theory Matter is made of atoms Atoms can not be divided into smaller pieces Unit 1 • Investigation III

Different elements are made of different kinds of atoms All atoms of an element are exactly alike Unit 1 • Investigation III

John Dalton thought that atoms looked like solid spheres. Unit 1 • Investigation III

J.J. Thomson Thought that the atom is a sphere of positive charge with negative charges spread equally throughout. Therefore, atoms have a neutral charge. Unit 1 • Investigation III

Ernest Rutherford Thought that the atom had a nucleus (center) that was all positive charge and electrons (negative) that float around it. Unit 1 • Investigation III

Neil Bohr Atoms have three particles protons, neutrons and electrons. Electrons exist in shells or energy levels around the nucleus. Unit 1 • Investigation III

Current Nuclear Model Atoms has three types of particles and the electrons exist in an electron cloud. Protons (positive) Neutrons (neutral) Electrons (negative) Unit 1 • Investigation III

Making Sense From Pudding & Clouds: Examine the date of the atomic evidence and then put the five models in the correct order of their introduction to the world of science. Unit 1 • Investigation III

(cont.) Five Models of the Atom Unit 1 • Investigation III

Check-Out Here is a Bohr model of a carbon atom. List two things this model tells you about atoms. List something this model does not tell you about atoms. Unit 1 • Investigation III

History of the Atom Foldable Create a tri-fold with the following information: Each Scientists idea of the atom including the persons name, description of what they thought and a picture of their idea of the atom. Must be colorful and displayable! Will be collected and graded!! Unit 1 • Investigation III

Wrap-Up All matter is made up of extremely small particles called atoms. These particles are too small to be seen even with a microscope. Science is theoretical and dynamic. Models and theories are continually being revised, refined, or replaced with new models and theories. Unit 1 • Investigation III

Alchemy Unit – Investigation III Lesson 2: Building Atoms

Copy these questions into your journal. Look at the following pictures and list three similarities and three differences. Unit 1 • Investigation III

ChemCatalyst A Bohr model of a helium atom and a beryllium atom are given below. Helium, He Berylium, Be (cont.) Unit 1 • Investigation III

The Big Question What does the periodic table tell us about the structures of different atoms? Unit 1 • Investigation III

You will be able to: Use the periodic table to identify the properties of an elements atom. Unit 1 • Investigation III

Atomic Number Atomic number is the number of protons in the nucleus of an atom. This number is above the chemical symbol. The number of electrons is always equal to the number of protons in a neutral atom. Ex. Lithium has 3 protons, therefore it also has 3 electrons Unit 1 • Investigation III

Mass Number Mass number is the number of protons plus the number of neutrons. You can find this by rounding the number beneath the chemical symbol. Also referred to as atomic mass because it is the mass of one atom of the element. Unit 1 • Investigation III

Atomic Weight 1. Atomic Weight is the decimal number that is found beneath the chemical symbol for an element. 2. It is an average of all the different types of atoms for that element. Unit 1 • Investigation III

Calculating the parts of the atom Mass number (# of protons + neutrons) minus Atomic Number (# of protons) ____________________________ Number of neutrons Unit 1 • Investigation III

How to read and use an element key Unit 1 • Investigation III

Activity Purpose: Label where the protons, neutrons and electrons are in these atoms. Beryllium Atom Fluorine Atom Carbon Atom (cont.) Unit 1 • Investigation III

(cont.) element chemical symbol atomic number # of protons # of electrons # of neutrons mass number atomic weight beryllium 5 fluorine 10 6 12 chlorine 18 35.45 lead 126 potassium 19 39 tin 70 tungsten 184 183.85 29 36 gold 118 Unit 1 • Investigation III

Making Sense If you know the atomic number of an element, what other information can you figure out about the atoms of that element? If you know the atomic number of an element, can you figure out how many neutrons an atom of that element has? Can you come up with a close guess? Explain. Unit 1 • Investigation III

Check-Out 1. Use your periodic table to identify the following elements: a) Atomic number 18 b) Has three electrons c) Atomic mass of 16.0 2. How do you think a gold atom is different from a copper atom? Unit 1 • Investigation III

Wrap-Up Each successive element has one more proton than the element preceding it. The atomic number is equal to the number of protons. (cont.) Unit 1 • Investigation III

(cont.) The number of electrons is equal to the number of protons (as long as the atom is neutral). The mass number is equal to the number of protons plus the number of neutrons (most of the mass is found in the nucleus). Unit 1 • Investigation III

Alchemy Unit – Investigation III Lesson 3: Subatomic Heavyweights

What is different about the two atoms? (Copy these questions into your journal) What is different about the two atoms? What is the atomic number of each atom? What is the mass number of each atom? Do you think they are both lithium atoms? Why or why not? Unit 1 • Investigation III

Use these pictures to answer the previous questions. A chemist investigating a sample of lithium found that some atoms have a lower mass than other atoms. The chemist determined that the structures of the two types of atoms would be similar to the two drawings below. (cont.) Unit 1 • Investigation III

The Big Question How do isotopes of an atom account for the atomic weight of an element? Unit 1 • Investigation III

You will be able to: Predict the isotopes of an element. Unit 1 • Investigation III

Notes Atoms of the same element that have different numbers of neutrons are called isotopes. Atomic mass units (amu) are “invented” measurement units of the atomic mass. Unit 1 • Investigation III

Notes While the element iron is defined as being made up of neutral atoms with 26 protons and 26 electrons, not every iron atom has the same number of neutrons. Atoms that have the same number of protons but different numbers of neutrons are called isotopes. (cont.) Unit 1 • Investigation III

Notes (cont.) What we call the atomic weight on the periodic table is actually the average atomic mass of that element’s naturally occurring isotopes. Isotopes have similar chemical properties in that they combine with other elements to form similar compounds. (cont.) Unit 1 • Investigation III

(cont.) Atomic Weight is the weighted average of the atomic masses of different isotopes taking into account their abundance. (cont.) Unit 1 • Investigation III

(cont.) Unit 1 • Investigation III

Activity Purpose: In this lesson you will investigate isotopes and how they affect atomic weight. (cont.) Unit 1 • Investigation III

(cont.) (cont.) boron atom 1 2 3 4 5 6 7 8 9 10 # protons # neutrons # electrons (cont.) Unit 1 • Investigation III

(cont.) Element Chemical Symbol Atomic Number Atomic Weight # of protons # of electrons # of neutrons Boron B 5 or 6 Chlorine 17 Lithium 6.94 Vanadium V 23 Nitrogen 7 Magnesium Argon Ar 39.9 21 or 22 Unit 1 • Investigation III

Check- Out Predict the isotopes of carbon, C. Which isotope is more abundant? How do you know? Explain why the atomic weights listed in the periodic table are not usually whole numbers. Unit 1 • Investigation III

Wrap-Up Elements may have anywhere from 2 to 10 naturally occurring isotopes. The atomic weight of an element listed on the periodic table is actually the average mass of the naturally occurring isotopes of that element. Isotopes have the same number of protons and electrons, but different numbers of neutrons. (cont.) Unit 1 • Investigation III

Isotopes are referred to by their mass numbers. (cont.) Isotopes of a single element exhibit similar properties in that they form similar compounds. Isotopes are referred to by their mass numbers. Unit 1 • Investigation III

Alchemy Unit – Investigation III Lesson 4: Life on the Edge

ChemCatalyst The three atoms below have similar reactivity and chemical behavior. Where are these elements located on the periodic table? What do you think might be responsible for their similar properties? (cont.) Unit 1 • Investigation III

(cont.) Unit 1 • Investigation III

The Big Question What accounts for the similar chemistry of elements in the same group? Unit 1 • Investigation III

You will be able to: Give the number of valence electrons for an element. Unit 1 • Investigation III

Activity Purpose: The various physical and chemical properties of the elements can be traced to the electrons. By studying electrons further we may be able to unlock the key to creating substances similar to gold. This lesson will reveal the arrangement of electrons within atoms. Unit 1 • Investigation III

(cont.) Five Models of the Atom Unit 1 • Investigation III

Making Sense Explain how you can determine the arrangement of an element’s electrons, from the element’s position on the periodic table. Unit 1 • Investigation III

Notes Bohr proposed that electrons could be found in different shells around the nucleus. Unit 1 • Investigation III

(cont.) (cont.) Unit 1 • Investigation III

The outermost shell of each drawing is called the valence shell. (cont.) The outermost shell of each drawing is called the valence shell. The valence shell contains the valence electrons. All other electrons are considered core electrons. Unit 1 • Investigation III

Check-In Provide the following information for element number 34. a) The element’s name and symbol. b) The number of protons in the nucleus. c) The total number of electrons for this element. d) The number of core electrons for this element. (cont.) Unit 1 • Investigation III

e) The number of valence electrons. (cont.) e) The number of valence electrons. f) The group number for this element. g) The names of other elements with similar chemistry. Unit 1 • Investigation III

Wrap-Up Electrons occupy different shells around the nucleus of an atom. Each electron shell can hold a specific maximum number of electrons. The valence electrons are in the outermost electron shell of an atom. Electrons that are not valence electrons are called core electrons. (cont.) Unit 1 • Investigation III

Elements with the same number of valence electrons have similar chemistry and are in the same group. Unit 1 • Investigation III

Alchemy Unit – Investigation III Lesson 5: Shell Game

ChemCatalyst The two drawings show two ways of representing the electron arrangement of the element calcium, Ca. Name at least two differences. Name at least two similarities. 1 2 3 4 1s 2s 2pp 3sp 3pp 3d 4sp 4pp Unit 1 • Investigation III

The Big Question How do electron subshells relate to the periodic table? Unit 1 • Investigation III

You will be able to: Identify an element based on its electron configuration. Unit 1 • Investigation III

Notes Electron shells are divided into electron subshells. Unit 1 • Investigation III

Activity Purpose: This lesson introduces you to electron subshells. You will explore how they are related to the periodic table. (cont.) Unit 1 • Investigation III

(cont.) 1s 2s 2pp 3sp 3pp 3d 4sp 4pp Unit 1 • Investigation III

(cont.) Electron configuration Element 1s22s1 1s22s22p3 nitrogen, N 1s22s22p63s23p5 1s22s22p63s23p64s23d6 1s22s22p63s23p64s23d104p2 1s22s22p63s23p64s23d104p65s24d105p4 tellurium,Te Unit 1 • Investigation III

Making Sense How is the organization and structure of the periodic table related to electron subshells? (cont.) Unit 1 • Investigation III

(cont.) Unit 1 • Investigation III

Notes An electron configuration is a list of all the subshells that have electrons for a given element. The number of electrons in a subshell is specified as a superscripted number. Unit 1 • Investigation III

Check-In Identify the element with the following electron configuration. 1s22s22p63s23p64s23d104p3 Unit 1 • Investigation III

Wrap-Up Electron shells can be divided further into subshells, referred to as; s, p, d, f. Each subshell can hold a specific maximum number of electrons. The s subshell can hold 2 electrons, the p subshell can hold 6, the d subshell can hold 10 electrons, and the f subshell can hold 14. (cont.) Unit 1 • Investigation III

(cont.) The periodic table can assist us in figuring out the sequence of filling the subshells with electrons. Chemists keep track of electrons and the subshells they are in by writing electron configurations. Unit 1 • Investigation III

Alchemy Unit – Investigation III Lesson 6: Go Figure

ChemCatalyst Consider the following electron configuration: 1s22s22p63s23p64s23d104p4 What element do you think is represented by this electron configuration? How many valence electrons do you think this element has? Explain your reasoning. Unit 1 • Investigation III

The Big Question Where are the valence electrons in electron configurations? Unit 1 • Investigation III

You will be able to: Write electron configurations and name valence electrons for an element. Unit 1 • Investigation III

Activity Purpose: This activity teaches you a shorthand way to keep track of electron arrangements and how to identify valence electrons. (cont.) Unit 1 • Investigation III

(cont.) (cont.) Element Electron configuration No. of valence electrons Identity of valence electrons 1s22s22p3 5 2s22p3 1s22s22p63s23p1 1s22s22p63s23p64s23d2 2 or 4 4s23d2 1s22s22p4 Chlorine 1s22s22p63s23p64s23d104p65s1 Barium (cont.) Unit 1 • Investigation III

(cont.) (cont.) Element Electron configuration No. of valence electrons Identity of valence electrons 1s22s22p63s23p64s23d104p65s24d105p6 Silver 1 or 2 5s2 Potassium Mercury 2 6s2 Terbium Chromium 2,3,4,5,6 4s23d4 (cont.) Unit 1 • Investigation III

(cont.) Element Electron configuration Valence electrons Lithium, Li [He] 2s1 2s1 Potassium, K [Ar] 4s1 4s1 Scandium, Sc [Ar] 4s23d1 4s2 3d1 Zinc, Zn [Ar] 4s23d10 4s2 Unit 1 • Investigation III

Making Sense If you know the electron configuration of an element, what other information can you figure out? List at least six things. (cont.) Unit 1 • Investigation III

Unit 1 • Investigation III

Check-In Write the electron configuration for bromine, Br. Write the noble gas electron configuration for Br. How many valence electrons does Br have? Explain. Unit 1 • Investigation III

Wrap-Up The noble gases can be used as placeholders in the periodic table when writing electron configurations. In the d-block or transition elements we find some exceptions to the rules when determining valence electrons. Unit 1 • Investigation III

Alchemy Unit – Investigation III Lesson 7: Technicolor Atoms

ChemCatalyst The ancient alchemists heated atoms to try to change them into gold. Knowledge of atomic structure assists us in figuring out what parts of an atom can be changed. Let’s say we started with a lithium atom and changed different parts of the atom. Look at the lithium atom below and four possible changes to it. What would we end up with in each case? (cont.) Unit 1 • Investigation III

Unit 1 • Investigation III

The Big Question What part of the atom is changed by heating? Unit 1 • Investigation III

You will be able to: Predict the color of the flame produced when heating a substance. Unit 1 • Investigation III

Activity Purpose: In this activity you will observe evidence that atomic structure is changed when atoms are heated. (cont.) Unit 1 • Investigation III

Keep long sleeves and clothing away from the flames. (cont.) Safety Note: Tie back long hair. Keep long sleeves and clothing away from the flames. (cont.) Unit 1 • Investigation III

(cont.) Note: Do not exchange wires. For each solution, only use the wire that is already in that solution. After you use the wire, be sure to put it back in the solution from which it came. (cont.) Unit 1 • Investigation III

Substance Name Color of Flame sodium carbonate potassium nitrate copper nitrate strontium nitrate potassium chloride sodium chloride copper sulfate strontium chloride sodium nitrate potassium sulfate copper wire copper penny Unit 1 • Investigation III

Making Sense The yellow color of the flame for sodium indicates that the sodium atoms changed in some way when they were heated. Consider the following possibility that the electron configuration of sodium changed from [Ne]3s1 to [Ne]4p1. What is the difference between [Ne]3s1 and [Ne]4p1? (Are the total number of electrons the same? Are the electrons in the same locations?) (cont.) Unit 1 • Investigation III

(cont.) Do you think gold can be made by changing the arrangement of electrons in atoms? Explain. Unit 1 • Investigation III

Notes Red Blue/Green Yellow/Orange Pink/Lilac (cont.) strontium nitrate strontium chloride Blue/Green copper nitrate copper sulfate copper solid copper penny Yellow/Orange sodium carbonate sodium chloride sodium nitrate Pink/Lilac potassium nitrate potassium chloride potassium sulfate (cont.) Unit 1 • Investigation III

Notes (cont.) Unit 1 • Investigation III

Check-In Predict the colors of the flames produced when heating the following substances. Explain your thinking. Copper carbonate Magnesium sulfate Unit 1 • Investigation III

Wrap-Up Electrons can move between subshells within an atom. An energy exchange occurs when electrons move farther away from the nucleus, or when they return to their original subshell. Moving electrons within an atom does not change the identity of the atom. Unit 1 • Investigation III