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In Your Element

2. Video: History of Atoms
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3. Who are these men?
In this lesson, we’ll learn about the men whose quests for knowledge about the fundamental nature of the universe helped define our views.

5. Democritus
400 BC
This is the Greek philosopher Democritus who began the search for a description of matter more than 2400 years ago.
He asked: Could matter be divided into smaller and smaller pieces forever, or was there a limit to the number of times a piece of matter could be divided?

6. I. History of Atomic Theory
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Democritus BC
Greek Philosopher
He named the smallest piece of matter “atomos,” meaning “not to be cut.”
3. He claimed that everything was composed of indivisible solid material called ATOMS

7. Democritus lacked the technology needed to test his theory and therefore could not perform experiments.

8. Atomos
To Democritus, atoms were small, hard particles that were all made of the same material but were different shapes and sizes.
Atoms were infinite in number, always moving and capable of joining together.

9. OOPS!
This theory was ignored and forgotten for more than 2000 years!

10. WHY?

11. B. Aristotle ( BC)
1. His view on atoms was that all particles were made of the elements earth, water, fire, and air.
2. Aristotle also thought that atoms could be divided into smaller and smaller pieces.

12. The eminent philosophers of the time, Aristotle had more respect, but ultimately his theory was wrong
Aristotle and Plato favored the earth, fire, air and water approach to the nature of matter. The atomos idea was buried for approximately 2000 years.

13. C. Dalton’s Model
1. In the early 1800s, the English Chemist John Dalton performed a number of experiments that eventually led to the acceptance of the idea of atoms.

14. Dalton’s Theory
2. He deduced that all elements are composed of atoms. Atoms are indivisible and indestructible particles.
3. Atoms of the same element are exactly alike.
4. Atoms of different elements are different.
5. Compounds are formed by the joining of atoms of two or more elements.

15. The structure of the atom
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A. The Ancient Greeks used to believe that everything was made up of very small particles. I did some experiments in 1808 that proved this and called these particles ATOMS:
Dalton
ELECTRON – negative, mass nearly nothing
PROTON – positive, same mass as neutron (“1”)
NEUTRON – neutral, same mass as proton (“1”)

16. II. What are ATOMS? Atoms are the basic building blocks of all matter
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Atoms are the basic building blocks of all matter
There are 90 naturally occurring Atoms
Atoms are made out of 3 basic particles
1. + = Protons –Carry a positive charge
2. Neutral = Neutron-Carry No Charge
3. - = Electrons –Carry a Negative Charge

17. Inside an Atom
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18. Bohr Configuration
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19. 1. If an electron weighted the size of a dime,
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D. Fun Facts
1. If an electron weighted the size of a dime,
a proton would weight the same as a gallon of milk!
2. Neutrons and Protons have almost the same mass

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21. E. Atoms always have as many Electrons as Protons
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E. Atoms always have as many Electrons as Protons
F. Atoms Usually have as many Protons as Neutrons.
1. Adding a proton makes a new kind of Atom
2. Adding a Neutron makes an Isotope
a. a heavier version of the atom

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25. III. Periodic Table History
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History
Dimitri Mandeleev was the first scientist to create the periodic table of elements.
The table of elements were ordered by increasing atomic weight and according to similar properties
a. much like the periodic table we use today

26. Mendeleev’s Original Periodic Table
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B. Why is the Periodic Table of Elements Important? 1. The periodic table is the most useful tool to a chemist. 2. We use it to make predictions 3. It organizes a lot of information about all the known elements. C. Today’s Periodic Table 1. Organized by increasing atomic number 2. Arranged by Periods (ROWS) and Groups (COLUMNS) 3. Atomic number increases as you move across a Period (row)

28. D. Mass and atomic number 1. Atomic Mass = Weight of the atom
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Particle
Relative Mass
Relative Charge
Proton 1 +1
Neutron
Electron
Very small -1
MASS NUMBER = number of protons + number of neutrons He 2 4
No two elements have the same number of protons .
SYMBOL
PROTON NUMBER = number of protons (obviously)

29. E. Mass and atomic number
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How many protons, neutrons and electrons? 1 11 16 H B O 1 5 8 23 35
238 Na Cl U 11 17 92

30. Periodic Table of Elements

31. Smallest Periodic Table in World
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34. F. Periods 1. Each horizontal row of elements is called a period.
2. The elements in a period are not alike in properties.
3. In fact, the properties change greatly across even given row.
4. The first element in a period is always an extremely active solid.
5. The last element in a period, is always an inactive gas.

36. G. Families / Groups
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1. Columns of elements are called groups or families.
2. Elements in each family have similar but not identical properties.
a. For example, lithium (Li), sodium ( Na), potassium (K), and other members of family IA are all soft, white, shiny metals.
3. All elements in a family have the same number of valence electrons.

38. H. Classifying Elements
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Elements are classified according to their properties.
There are 3 Main categories of Elements

40. a. Metals Metals are good conductors of heat and electricity.
Metals are shiny.
3. Metals are malleable (can be pounded into thin sheets).
4. A chemical property of metal is its reaction with water which results in corrosion.

41. b.Non-Metals
Non-metals are poor conductors of heat and electricity.
Non-metals are not ductile or malleable.
3. Solid non-metals are brittle and break easily.
4. They are dull.
5. Many non-metals are gases.
Sulfur

42. Properties of Metalloids
Metalloids (metal-like) have properties of both metals and non-metals.
They are solids that can be shiny or dull.
They conduct heat and electricity better than non-metals but not as well as metals.
They are ductile and malleable.
Silicon

43. Horizontal rows are called PERIODS
Periodic table
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Mendeleev
The periodic table arranges all the elements in groups according to their properties.
Vertical columns are called GROUPS
According to their properties
Horizontal rows are called PERIODS

44. The Periodic Table
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B. Fact 1: Elements in the same group have the same number of electrons in the outer shell (this corresponds to their group number) H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Fe Ni Cu Zn Br Kr Ag I Xe Pt Au Hg
These elements have __ electrons in their outer shells
These elements have __ electrons in their outer shell
E.g. all group 1 metals have __ electron in their outer shell

45. The Periodic Table
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C. Fact 2: As you move down through the periods an extra electron shell is added:
E.g. Lithium has 3 electron in the configuration 2,1 H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Fe Ni Cu Zn Br Kr Ag I Xe Pt Au Hg
Sodium has 11 electrons in the configuration 2,8,1
Potassium has 19 electrons in the configuration __,__,__,__

46. D. Fact 3: Most of the elements are metals:
The Periodic Table
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D. Fact 3: Most of the elements are metals:
These elements are metals H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Fe Ni Cu Zn Br Kr Ag I Xe Pt Au Hg
These elements are non-metals
This line divides metals from non-metals

47. The Periodic Table
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E. Fact 4: (Most important) All of the elements in the same group have similar PROPERTIES. This is how I thought of the periodic table in the first place. This is called PERIODICITY. H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Fe Ni Cu Zn Br Kr Ag I Xe Pt Au Hg
E.g. consider the group 1 metals. They all:
Are soft
Can be easily cut with a knife
React with water

48. IV. Matter
A. All matter is composed of atoms and groups of atoms bonded together, called molecules.
1. Substances that are made from one type of atom only are called pure substances.
2. Substances that are made from more than one type of atom bonded together are called compounds.
3. Compounds that are combined physically, but not chemically, are called mixtures.

49. V. Burning Elements
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When you burn something it reacts with Oxygen in the air
1. Metal + Oxygen = Metal Oxide
2. Magnesium + Oxygen = Magnesium Oxide
a. Magnesium Oxide is NOT an element it is a COMPOUND (MgO)
3. It would take too long to write out all compounds so they are written in Formulas
a. Magnesium Oxide’s Formula = MgO
b. This tells us that MgO is a compound and NOT an element

50. VI. Reactants & Products
1. are the ingredients in a reaction –what you put in
B. PRODUCTS
1. Created or made by the reaction-what you get out
Product
Reactants
Magnesium
Oxide
Oxygen
Magnesium

51. Magnesium reacts with oxygen to make magnesium oxide.
magnesium + oxygen magnesium oxide
Iron reacts with oxygen to form iron oxide.
iron oxygen iron oxide
Sulphur reacts with oxygen to form sulphur dioxide.
sulphur oxygen sulphur dioxide
Glucose and oxygen react together to form carbon dioxide and water.
glucose + oxygen carbon dioxide + water
Hydrochloric acid reacts with sodium hydroxide to form sodium chloride and water.
hydrochloric acid + sodium hydroxide sodium chloride + water

52. Sodium chloride can be made by reacting sodium and chlorine together.
sodium chlorine sodium chloride
Carbon dioxide can be made by reacting carbon and oxygen together.
carbon oxygen carbon dioxide
If you heat copper carbonate strongly, it turns into carbon dioxide and copper oxide.
copper carbonate carbon dioxide + copper oxide
Hydrogen peroxide turns into water and oxygen if you leave it in the sunlight.
hydrogen peroxide water oxygen
Aluminium oxide can be split up into aluminium and oxygen (but it is very expensive).
aluminium oxide aluminium oxygen