# Presentation: 464139

## Introduction

***Gail Rohrbach***

- Elements 2002 Workshop

**What are the Elements**
**and**
**Where do they come from?**

- Elements 2002 Workshop

- August 5, 2002

**Notes:**
Title slide for Introduction:

Possibly have this on screen, or leave screen off for beginning; either way, turn screen off shortly after being introduced and begin interactive dialogue with audience.  Ask:
    What is an element? 
Get them to give definitions/ideas.  Don’t try for a “right” or “best” answer - the point is to get lots of definitions out there, to truly explore what the members of the audience think of when they hear the word “element.”  How would they define it to a class?  Would it depend on the class they were teaching?

[next slide]

## What is an Element?	

**element ***(n) - *
- 1. A fundamental, essential, or irreducible constituent of a composite     entity.  2. [**elements**] The basic assumptions or principles of a subject.
- 3. *Mathematics* a. A member of a set. b. A point, line, or plane. c. A part of a geometric configuration, such as an angle in a triangle ...
- 4. *Chemistry & Physics * any of more than 100 fundamental substances that consist of atoms of only one kind and that singly or in combination constitute all matter. 5. One of four substances, earth, air, fire, or water, formerly regarded as a fundamental constituent of the universe.  6. *Electricity* The resistance wire in an electrical appliance such as a heater or an oven.  7. [**elements**] The forces that constitute the weather, especially severe or inclement weather: “*outside paint that had been damaged by the elements*.”  8. An environment naturally suited to or associated with an individual: “*The business world is her element.” ... * 11. [**elements**]  The bread and wine of the Eucharist.

- Elements 2002 Workshop

- August 5, 2002

**Notes:**
(Option: may advance to this slide, and hit mouse to bring up “What is an Element?” line, and then start discussion mentioned on previous slide.)
After the audience has discussed definitions of “element,” click mouse to bring up this slide.  Slide will begin with just title at top (questioning “What is an Element?”).  Introduce with something like, “We’ve talked about what an element is - now let’s see what the dictionary says.”  Click to reveal dictionary definition(s).  Note that the chemical definition is not the only one.  In particular, the word “elements” can mean several different things: weather, basic assumptions underlying a subject, even religious context.
Discuss: what do all these definitions have in common?  What’s the underlying concept?  [Things that are fundamental? Constituents?]
Point out: students coming to class (particularly in lower grades) may have other ideas about what an element is, since the word is so prevalent in our language. We’re talking about the “chemical elements” here.  Discuss with students *their* idea of what an element is.  Engage them in the quest to discover what “The Elements” are in physical science.

## What is an Element?	

_**Sun:**_
- Air and Fire

_**Cloud:**_
- Water and Air

- Elements 2002 Workshop

- August 5, 2002

**Notes:**
(Begin with empty slide showing only the title at top - do not advance yet.)
Many ancient peoples thought the Universe was made up of various combinations of a few “fundamental” substances.  The ancient Greeks, for example, believed there were 4 basic “elements”: (accompany with mouse clicks) Earth, Air, Fire, and Water. These elements could combine to create everything else observed in the Universe (click mouse again, revealing background photo).
For example, the Sun would be a combination of Air and Fire (click mouse to bring up label showing this).  Clouds would be a combination of Water and Air (click mouse again).  And so on - you get the idea and can see the appeal of this kind of scheme. 
Note: some other ancient cultures had different ideas of what the fundamental substances or “elements” might be.  Potentially, students could research other cultures and report on what these people believed - ancient China, Japan, possibly Babylon, Egypt, or the ancient peoples of greater Africa, India, or South America.
So, we have a Universe made up of a few, fundamental “elements”.  Does this remind you of another idea commonly attributed to the ancient Greeks?   What else was said to be a building block, something that everything in the Universe was made up of?  (Atoms)
[Next slide]

## What is an Element?	

**What’s the difference between an**
**element ****and an ****atom****?**

*(if both are fundamental building blocks of matter...?)*

- Elements 2002 Workshop

- August 5, 2002

**Notes:**
This may seem like a simple, or “silly” question, but it’s something a lot of students may be confused about.  They’re told matter is made up of atoms, and that the chemical elements combine to make up all matter.  What’s the difference?  Discuss this.  Ask for answers from the audience.  See if together we can puzzle out how best to explain these two different types of “building blocks.”  
After discussion, click mouse to reveal good “working”  definitions of what atoms and elements are.  [Next slide]

## What is an Element?	

**atom: **a tiny, chemically indivisible particle made up of protons, electrons, and sometimes neutrons. An atom is identified by the number of protons in its nucleus, referred to as its “atomic number.”

**element: **a substance composed solely of atoms with the same atomic number (i.e. atoms having an identical number of protons in each nucleus).

- Elements 2002 Workshop

- August 5, 2002

**Notes:**
There are many definitions of “atom”  and “element.”  The most common dictionary definitions define each in terms of the other: an “atom” is defined as the smallest particle of an element which still has all the properties of the element, and an “element” is defined as a substance made up of atoms which all have the same atomic number.  To break this cycle, we try to define an atom as a physical particle, and then describe an element in terms of atoms.
Ask the audience how the definitions on this slide compare with the previous discussion of atoms and elements.  If the “dictionary” definition of atom has been mentioned, discuss how this definition came about.  Look at how “element” is defined above, and see if this explains why an atom could be defined as “the smallest particle of an element which still has all the properties of the element.”  This leads naturally to the next slide, about the Periodic Table.  

## What is an Element?	

**Sample**

**Periodic Table **
**of the Elements**

- Elements 2002 Workshop

- August 5, 2002

**Notes:**
So, what does all this mean?  We’ve talked about elements and atoms. What’s the periodic table of elements?  What’s shown here? Have the audience discuss what this is - what does it represent?  
We just talked about elements as substances comprised only of atoms of one type (identical atomic number). Why do the elements’ names appear next to specific numbers? Is that element the name only for a collection of those atoms, or is a single atom also considered to be that element?  Introduce the definition of atom as the “smallest particle of an element retaining all the properties of that element,” if it hasn’t already been discussed.
Bottom line: atomic number and element name are two different ways of identifying an atom by its number of protons.  The atomic number implies the element name, and visa versa.  Note that we can change the number of electrons or neutrons in an atom, and it still belongs to the same element: it has the same atomic number and the same number of protons. 
-> Atoms with the same number of protons but varying number of neutrons are called “isotopes” of each other.  May give examples, depending on sophistication of audience or content of later talks.  (E.g., Hydrogen and Deuterium, or Carbon-14 and Carbon-16.  This introduces the concept of atomic weights.) 
Why are the elements arranged in the order they are?  What’s different from one element to the next?  Note that they are arranged in order of increasing atomic number, left to right, top to bottom.  Atomic number = no. of protons, so this is simply a list of the names of atoms by increasing no. of protons. Essentially , the names of the elements are the names for all the different “types” of atoms we know of.

## What is an Element?	

**All the normal matter in the Universe is made up of combinations of these elements:**
**Everything we see around us is just ~100 different kinds of atoms (the elements), combined in various ways.**

- So, we’re back to the Ancient Greeks:
- All matter is made up of a “few” fundamental substances -

- Elements 2002 Workshop

- August 5, 2002

**Notes:**
This summarizes the conclusions/concepts from discussion of previous slide.
Note that in the second item, “different kinds of atoms combined in various ways,” refers to atoms of different elements combining to form molecules, compounds, etc.

## Where do the Elements Come From?

** ****Why do we have only these elements?  Why aren’t there more?  (Why aren’t there an infinite number?)**
** ****Do all the elements exist in equal quantities? If not, why not?**
** ****How can we tell?**

- Elements 2002 Workshop

- August 5, 2002

**Notes:**
Discuss these questions.  Do all the elements we see on Earth appear in equal quantities?  Is gold as plentiful as oxygen, or carbon?  Why?  Let the audience range where they want with this - they may get into discussion of total weight vs. number of atoms of different elements, or may explore whether larger quantities of some elements are buried deep inside the earth.  Gently guide them around to the discovery that the elements are not equally plentiful. Do they think this is only true for Earth, or might it be true for the rest of the Universe, as well.
How can we tell?
Stress that inquiry, the asking of questions, is fundamental to science. Science is about asking questions and then finding ways to answer them.  It’s puzzle-solving.  When we talk about Science, we’re really referring to two things at once: the process of inquiry and testing which is the practice of science, and the body of theories and knowledge which have resulted from this practice. Too often, students only think of the latter.  It’s important to familiarize them with the physical world (ie., current theories and facts revealed by science), but even more important for them to understand the process by which these facts were attained.  (Switch to next slide any time during this discussion)

## Where do the Elements Come From?

-  How and when did the elements come to exist?
-  Why do we have only these elements?  Why aren’t there more?     Why aren’t there an infinite number?
-  Do all the elements exist in equal quantities? If not, why not?
-  How can we tell?

**We’ll spend the rest of this workshop **
**exploring these questions**

- Elements 2002 Workshop

- August 5, 2002

**Notes:**
Underlines the fact that what we’ve been discussing are the fundamental questions this workshop seeks to answer.  See previous slide for emphasis on the asking of questions in science.  This isn’t just a workshop summary.  These are the questions that this group, as “scientists,” should be asking.  Keep your eyes open in the upcoming talks for answers to these questions.  (Not just “when,” and “why,” but “how do we know?”)

## Where did the Elements come from?

***Sneak Preview:***

** ****All the matter that exists formed at once, a very long time ago**

**- shortly after The Big Bang**

** ****Since then, matter has combined and recombined - making different types of atoms - but the total amount of matter hasn’t changed: ****no matter is created or destroyed**** **

*“**And he said this thing was so small -- this part of me was so small it couldn’t be seen -- but it was there from the beginning of the world.”*
* *-- Tillie, from “The Effects of Gamma Rays on Man-In-The-Moon Marigolds”

- Elements 2002 Workshop

- August 5, 2002

**Notes:**
Reveal first part of first bulleted point, then prompt audience.  See when they think all matter might have been formed - bring them to the idea of the Big Bang.  [then reveal second half of first bullet]
Go to second bullet: it’s important to realize that the matter which formed so long ago is still the matter we see around us today - it was all formed then, and has combined and recombined until it’s now the matter that makes up our bodies, our planet, and all the things on it.  Just like in Tillie’s speech!
Note: some may ask about matter and energy - the fact that matter can be converted to energy, and visa versa.  Can “new matter” be made out of this energy, so that, in a sense, matter is still being created, even today?  Since matter and energy are equivalent, it’s more correct to say that the total amount of matter & energy doesn’t change - matter combines and recombines, and certain amounts of energy are liberated or absorbed along the way.   The total quantity of energy-matter created in the Big Bang is still the amount we have today (as far as current theories tell us - more on that in upcoming talks!).  The story of the elements is, in fact, the story of how energy and matter have interacted over time to create the diversity of matter we know today.  
Watch for this theme throughout the upcoming presentations - notice that every element results from the absorption or liberation of energy, as well as matter.