1. Atoms and elements
8th Grade
Lesson 7

2. The standards The standards for this lesson are
Recognize that all matter consists of atoms; identify the atomic mass and number, number of protons and electrons from the periodic table.
Identify atoms as the fundamental particles that make up matter.
Explain that all matter has properties that are determined by the structure and arrangement of its atoms.

3. pretest
Number to five.
#1 What is the chemical symbol for iron?

4. Pretest #2
Sodium (Na-atomic number 11) is an element that is found in table salt. Explain how many electrons are in a neutral atom of sodium.

5. Pretest #3
Which atomic particle is positively charged?

6. Pretest #4
You are an electron involved in chemical reactions. Where are you found?

7. Pretest #5
What is the atomic number of an atom that contains 26 protons, 29 neutrons, and 26 electrons? How do you know?

8. First-vocab
By the end of this lesson, you will be able to explain what these words mean. List them now. Skip a few lines.
Atom
Element
Nucleus
Proton
Neutron
Electron
Electron cloud
Energy level
Atomic number
Neutral
Atomic mass
Chemical symbol

9. What you will learn Everything around us has mass and takes up space.
Everything around us-even living things-are made out of matter.
So, what makes up matter?
In this lesson, we will discuss the basic building blocks of all the things around us.

10. So, what’s the matter? What do you think matter is?
Matter describes all of the physical substances around us.
Your pencil, your body, the table, the parts of experiments are all made of matter.
If it is matter, it can be seen, tasted, smelled, touched, and measured.
Matter does not, however, include heat, sound, or light.

12. Atoms and elements What is an atom?
They are the basic building blocks of most of the matter around you.
Matter is made from atoms.
There are different kinds of atoms.
Each kind is an element.
An element is a pure substance that cannot be broken down into simpler substances by ordinary means.

13. The elements We have looked at several elements. Where are they?
About 118 elements have been discovered from all over the world.
Ninety of these are found in nature.
The rest are man made.
The synthetic elements will only last a short time before they break down.
Tell me five natural elements.

14. An atom is the smallest particle of an element that has all the properties of that element.
So, an atom of gold would be one particle of gold.
The atoms of every element are different.
To understand how the atoms of each element are different, we look at the particles that make up each atom.

16. The parts of an atom Every atom has four main parts.
The nucleus-the core of the atom. The nucleus of most atoms if made up of two kinds of subatomic particles: protons and neutrons.
The protons-carry a positive charge +
The neutrons-carry no charge N
The electrons-carry a negative charge -

18. The Masses
The masses of protons and neutrons are measured in atomic mass units (amu).
Protons have a mass of about 1 amu.
Neutrons have a mass of about 1 amu.
The mass of electrons is insignificant compared with the mass of protons and neutrons.
Particle
Charge
Symbol
Mass (amu)
Location
Proton
Positive +
1 amu
Nucleus
Neutron
Neutral
0 or n
Electron
Negative -
0 amu
Electron cloud

19. More about electrons…
The electrons move around the atom in an area outside the nucleus.
This area is called the electron cloud.
The electron cloud is organized into energy levels.
There are several energy levels in an atom.
The outermost energy level is the level where chemical reactions take place.
During these chemical reactions, atoms gain, lose, or share the electrons in the outermost level.

20. The Electron Cloud of Uranium

21. Electron Clouds/shells
Electron rings can only hold a certain number of electrons.
The first ring holds 2 Electrons.
The second ring holds 8 Electrons.
The third ring holds 18 Electrons.
The fourth ring holds 36 Electrons.
That gets us through element 64-Gadolinium

22. Elements and subatomic particles
The properties of an element are determined by the structure of its atoms. So, gold is gold because of its atoms and their structure.
The number of protons in an atom is its atomic number.
The atomic number is the main feature used to distinguish the atoms of different elements.
We have used atomic numbers in our look at the elements.
No two elements have the same atomic number.

23. Atomic numbers The atomic number is the number of protons in an atom.
In a neutral atom, the number of protons + equals the number of electrons -.
For example, oxygen has eight protons.
Therefore, its atomic number what?
And, how many electrons does it have?
The number of neutrons, however, is not unique.
Most carbon atoms have six neutrons, but they some have seven or even eight neutrons.
However, they are all carbon because they have six protons.

24. Atomic mass
The atomic mass of an atom is the number of protons plus the number of neutrons. It is measured in amu.
So, if carbon has six protons and six neutrons, what is its atomic mass?
12 amu.
Remember that electrons are so small that their mass is insignificant.
Therefore, only the protons and neutrons in the nucleus matter.

25. Chemical symbols
A chemical symbol is a one or two letter code used to symbolize an element.
What is C?
carbon
What is B?
Boron
What is Be?
A verb. Ha! Beryllium
How about H?
The symbols are often based on the Latin word for the element. For example, iron is Fe.

26. Sum it up… With your lab partner, review these thoughts-
The nucleus of an atom is made up of what?
The atomic number is the what?
The atomic mass is the what?
What charge does a proton have?
What charge does an electron have?
What charge does a neutron have?
What are electron rings for?

27. The nucleus is made of protons and neutrons.
The atomic number is the number we use to identify the element-as in Elemental Mondays.
The atomic number=number of protons.
The atomic number=number of electrons.
The number of protons=number of electrons.
Atomic mass (will be a large number)-atomic number (will be a small number) =number of neutrons.
The electron rings hold electrons.
The protons determine the element, but the electrons determine the chemical reaction.

28. Now, apply what you have learned…
With your lab partner, I want you to fill out all the information you can about an element-mass, number, number of protons, etc.
You get to pick the element.
The catch-no technology. Use your brain.
Be ready to present also.

29. posttest Let’s try the pretest again.
#1 What is the chemical symbol for iron? Fe
#2 Sodium (Na-atomic number 11) is an element that is found in table salt. Explain how many electrons are in a neutral atom of sodium.
If the atomic number is 11, then the number of electrons is 11. The atomic weight is the number of protons. Protons = electrons.

30. Posttest #3 Which atomic particle is positively charged?
The proton is positive; the electron is negative; the neutron is neutral.
#4 You are an electron involved in chemical reactions. Where are you found?
You are found in the electron cloud in the last energy level.
#5 What is the atomic number of an atom that contains 26 protons, 29 neutrons, and 26 electrons? How do you know?
The atomic number is the number of protons. Therefore, the atomic number is 26.
Bonus! What element is it?
It is iron.

31. Finally, the standards
Recognize that all matter consists of atoms; identify the atomic mass and number, number of protons and electrons from the periodic table.
Identify atoms as the fundamental particles that make up matter.
Explain that all matter has properties that are determined by the structure and arrangement of its atoms.
On a CPOP, explain to me three things you learned today that you did not know. Also tell me one question you have after this lesson.

32. Let’s Start with a lab Is it magic, or is it science? Let’s see.
What you will need-
Water
A measuring cup
Food coloring
A clear container-a plastic cup
A Sharpie
Rubbing (isopropyl) alcohol
A spoon or other mixing device
Don’t get the alcohol in your eyes.

33. The Procedure Take notes. You will be combining two liquids.
You will combine one cup of water with one cup of alcohol.
First, let’s form a hypothesis.
The question-How much of the final liquid will you have?
Now, we try it…

34. What you will do-
Carefully measure two cups of water and pour it into the clear cup.
Mark the top of the water.
Pour the water back out.
Pour one cup of water back in.
Mix a few drops of food coloring in the water.
Next, carefully measure one cup of rubbing alcohol.
Pour it into the cup of colored water.
Now, read how much of the final liquid you have.
Prepare your data.
Write your conclusion.
Can you explain what occurred?

35. What happened? Magic or science? Science!
When you combined the two liquids, some of the alcohol molecules found their way into the spaces between the water molecules.
What are molecules?
What elements were involved here?
How does this happen?
That is what we are about to learn!