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Elements & Atoms
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Essential Question
How can I use the periodic table to understand chemical and physical properties of an element?
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An atom refresher
Matter is anything that takes up space and has mass.
All matter is made of atoms
Atoms are the building blocks of matter, sort of how bricks are the building blocks of houses.
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An atom refresher
An atom has three parts:
Proton = positive
Neutron = no charge
Electron = negative
The proton & neutron are found in the center of the atom, a place called the nucleus.
The electrons orbit the nucleus.
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What are elements?
Elements are the alphabet to the language of molecules.
To make molecules, you must have elements.
Elements are made of atoms. While the atoms may have different weights and organization, they are all built in the same way.
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ISOTOPE VIDEO
It only shows the first part without a subscription. You do not need to see the other part of the movie, just until it stops.
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More about Elements..
Elements are the building blocks of all matter.
The periodic table is a list of all of the elements that can build matter. It’s a little like the alphabet of chemistry.
The periodic table tells us several things…
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Periodic Table
Atomic Number:
Number of protons and it is also the number of electrons in an atom of an element. 8
Element’s Symbol: An abbreviation for the element. O
Oxygen
Elements Name
Atomic Mass/Weight:
Number of protons + neutrons. 16
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Atom Models
There are two models of the atoms we will be using in class.
Bohr Model
Lewis Dot Structure
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Bohr Model
The Bohr Model shows all of the particles in the atom.
In the center is circles. Each circle represents a single neutron or proton. Protons should have a plus or P written on them. Neutrons should be blank or have an N.
In a circle around the nucleus are the electrons. Electrons should have a minus sign or an e. - + + -
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12. Electrons have special rules….
You can’t just shove all of the electrons into the first orbit of an electron.
Electrons live in something called shells or energy levels.
Only so many can be in any certain shell.
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Nucleus
1st shell
2nd shell
3rd shell
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14. Electrons have special rules….
You can’t just shove all of the electrons into the first orbit of an electron.
Electrons live in something called shells or energy levels.
Only so many can be in any certain shell.
The electrons in the outer most shell of any element are called valence electrons.
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15. What is the Periodic Table of Elements?
The Periodic Table of Elements is a way of organizing the elements in relation to each other so it is easy to find elements that have similar properties.
Why is that helpful?
It allows scientists to make predictions and explain events.

16. Here is a “periodic” table. What is it?

17. The columns are called “GROUPS” or families.
What is represented by the groups on this periodic table?
DAYS

18. The rows are “PERIODS”. WEEKS
What information is in the horizontal periods?
WEEKS

19. ? ? Certain information is missing.
How would you find the missing data?
Group 5 ? ?
Period 3

20. Periods Each row is called a “period”
The elements in each period have the
same number of electron shells
1st Period = 1 Shell
2nd Period = 2 Shells
3rd Period = 3 Shells
4th Period = 4 Shells
Hint:
A period comes at the end of a sentence--a horizontal line.

21. or Families 1 Groups Group 8 = 8 electrons Group 1 = 1 electron
Except for He, it has 2 electrons
Group 2 = 2 electrons 1 18
Each column is called a “group” or family. 2
Each element in a group has the same number of electrons in its outer orbital, also known as its outer shell.
The electrons in the outer shell are called “valence electrons.”
Hint: Your Family tree is vertical.

22. Transition Metals
Transition Metals have slightly different rules for shells and valence electrons.
This is something you will learn about in High School Chemistry.
For now, assume they each have two valence electrons.

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Periodic Table video
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24. How does your periodic table compare?
Let's practice finding
number of shells and valence electrons.
Use the periodic table.

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26. Determine the number of shells and the number of valence electrons for:
Carbon - C
2nd Period = 2 shells
4th Group =
4 valence
electrons

27. Determine the number of shells and the number of valence electrons for:
Sodium - Na
3rd Period = 3 shells
1st Group =
1 valence
electron

28. Ne For practice purposes Name the element. Number of shells ?
Valence electrons ?

29. Ne For practice purposes 1 Name the element. Number of shells ?
Valence electrons ?
Neon
2nd Period = 2 shells
8th Group = 8 valence
electrons 1

30. H For practice purposes Name the element. Number of shells ?
Valence electrons ?

31. H For practice purposes Name the element. Number of shells ?
Valence electrons ?
Hydrogen
1st Period = 1 shell
1st Group = 1 valence
electron

32. Be For practice purposes Name the element. Number of shells ?
Valence electrons ?

33. Be For practice purposes Name the element. Number of shells ?
Valence electrons ?
Beryllium
2nd Period = 2 shells
2nd Group = 2 valence
electrons

34. S For practice purposes Name the element. Number of shells ?
Valence electrons ?

35. S For practice purposes 1 Name the element. Number of shells ?
Valence electrons ?
Sulfur
3rd Period = 3 shells
6th Group = 6 valence
electrons 1

36. K For practice purposes Name the element. Number of shells ?
Valence electrons ?

37. K For practice purposes Name the element. Number of shells ?
Valence electrons ?
Potassium
4th Period = 4 shells
1st Group = 1 valence
electron

38. He For practice purposes Name the element. Number of shells ?
Valence electrons ?

39. He For practice purposes 1 Name the element. Number of shells ?
Valence electrons ?
Helium
1st Period = 1 shell
8th Group = 2 valence
electrons 1
Helium is the exception in Group 18.
Since it has just one shell, that shell can only fit 2 electrons instead of 8.
It is in this group because all the elements have a full outer shell.

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So let’s try it….
How to draw a Lithium atom
First, look at the Periodic Table
Second, determine the number of protons the atomic number)
Then determine the number of neutrons (Atomic mass – atomic number)
Then determine the number of electrons the atomic number) 3 Li
Lithium 7
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So let’s try it….
Protons = 3 3 Li
Lithium 7 - + + + - -
Electrons = 3
2 in the 1st shell, 1 in the 2nd shell
Neutrons = 4
(7-3=4)
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Lewis Dot Structure
The Lewis Dot Structure is a bit different from the Bohr model.
It only shows the element symbol and it’s outer most electron shell. + - • O • • •
• •
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43. Elemental Properties and Patterns
Periodic Trends
Elemental Properties and Patterns

44. The Periodic Law
Dimitri Mendeleev was the first scientist to publish an organized periodic table of the known elements.
He was perpetually in trouble with the Russian government and the Russian Orthodox Church, but he was brilliant never-the-less.

45. The Periodic Law
Mendeleev even went out on a limb and predicted the properties of 2 at the time undiscovered elements.
He was very accurate in his predictions, which led the world to accept his ideas about periodicity and a logical periodic table.

46. The Periodic Law Mendeleev understood the ‘Periodic Law’ which states:
When arranged by increasing atomic number, the chemical elements display a regular and repeating pattern of chemical and physical properties.

47. The Periodic Law
Atoms with similar properties appear in groups or families (vertical columns) on the periodic table.
They are similar because they all have the same number of valence (outer shell) electrons, which governs their chemical behavior.

48. Valence Electrons
Do you remember how to tell the number of valence electrons for elements?
In the transition metals, most have 2 valence e-, some only have 1.

49. A Different Type of Grouping
Besides the 4 blocks of the table, there is another way of classifying element:
Metals
Nonmetals
Metalloids or Semi-metals.
The following slide shows where each group is found.

50. Metals, Nonmetals, Metalloids
There is a zig-zag or staircase line that divides the table.
Metals are on the left of the line, in blue.
Nonmetals are on the right of the line, in orange.

51. Metals, Nonmetals, Metalloids
Elements that border the stair case, shown in purple are the metalloids or semi-metals.
There is one important exception.
Aluminum is more metallic than not.

52. Metals, Nonmetals, Metalloids Show the line on your periodic table

53. Metals, Nonmetals, Metalloids Label metals, metalloids, & nonmetals

54. Identify the two elements that are liquid at room temperature

55. Identify the elements that are a gas at room temperature
All of the gray clouds should indicate which elements are a gas at room temperature

56. Metals, Nonmetals, Metalloids
How can you identify a metal?
What are its properties?
What about the less common nonmetals?
What are their properties?
And what the heck is a metalloid?

57. Metals
Metals are lustrous (shiny), malleable, ductile, and are good conductors of heat and electricity.
They are mostly solids at room temp.
What is one exception?

58. Nonmetals Nonmetals are the opposite.
They are dull, brittle, nonconductors (insulators).
Some are solid, but many are gases, and Bromine is a liquid.

59. Metalloids Metalloids, aka semi-metals are just that.
They have characteristics of both metals and nonmetals.
They are shiny but brittle.
And they are semiconductors.
What is our most important semiconductor?